What controls the southern range of willows?

Many willows (Salix spp.) grow in northern states but do not grow in southern states, for example Salix viminalis.

What mechanisms control the southern range of temperate hardwoods such as willow? Is it disease? Temperature sensitivity of respiration? Water use efficiency?

The distribution of temperate hardwood forests, as well as deserts, tundras, savannahs, and other ecosystems, is determined primarily by average climate conditions, specifically average annual temperature and precipitation. You can see how biomes are related to climate in this figure, taken from Whittaker (1975):

Temperate forests tend to be between 2.5-17°C, and between 800-2500 mm precipation. These are not exact boundaries but reflect long-term climate conditions. As climate changes, so will the distribution of the biomes.

Temperature is important in many ways. For example, most temperate trees go dormant during the winter. This requires metabolic preparation by the tree. If the weather turns cold too fast, then the trees may be be properly prepared. Alternatively, if the weather warms to quickly the trees may not be able to come out of dormancy properly. This technical report (Coder 2011) provides more detail.

The precise mechanism that restricts the distribution of any one species would require experimental determination. As it turns out, Populus trichocarpa (black cottonwood), plus other Populus and Salix (all in the family Salicaceae) are quickly becoming model organisms for study. This should shed more light on specific distribution limitations, such as changes in soil nutrients, light intensity, or other environmental parameters. There are now regular symposia held on these model organisms. You can read an introduction to one symposium here (Tognetti et al. 2011).

As a side note: One must be careful about the mapped distributions of popular trees like willows. Many species, including Salix viminalis, have been introduced far outside their native range, including through out the eastern United States, as shown by the map you linked to. The native distribution of the species is the Palearctic (Eurasia), shown here.

Literature Cited

Coder, K.D. 2011. Trees & cold temperatures. Environmental Tolerance Series WSFNR11-12, Warnell School of Forestry and Natural Resources, University of Georgia, USA.

Tognetti, R. et al. 2011. Fifth international poplar symposium: Poplars and willows: From research to multipurpose trees for a bio-based society.

Whittaker, R.H. 1975. Communities and Ecosystems. MacMillan Publishing, New York, USA.

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Detailed Information


Male and female flowers are on separate plants (dioecious) in spike-like clusters (catkins) at the tips of short branchlets or from buds along 1 year old branches, emerging before the leaves. Male catkins are short cylindric, ¾ to 1½ inches long, the flowers densely packed, each flower with 2 stamens, the tips (anthers) initially red to purple, turning yellow. Female catkins are ¾ to 2½ inches long, the flowers moderately to densely crowded on the spike, bulbous at the base with a long beak, covered in short silky hairs, and on slender stalks .5 to 1.1 mm long. At the base of each male and female flower stalk is a tiny, dark brown to blackish, scale-like bract densely covered in long, straight hairs.

Leaves and stems:

Leaves are alternate, 1½ to 4¾ inches long, to ¾ inch wide, 4.5 to 11 times as long as wide, narrowly elliptic to lance-linear, widest near or below the middle, pointed at the tip, wedge-shaped to somewhat rounded at the base, toothless, the edges often rolled under (revolute) especially near the base. The upper surface is dark green, slightly glossy, hairless to sparsely hairy, with a strong network of indented veins the lower surface is silvery-white from a dense covering of silky, straight to somewhat tangled hairs.

Leaf-like appendages at the base of the leaf stalk (stipules) are mostly absent or obscure. New leaves are yellowish to reddish and densely white-hairy, sometimes with a few rusty-colored hairs. New branchlets are yellowish and mostly hairless, becoming dark reddish to purplish-brown the second year, often with a whitish waxy coating.

Stems are usually multiple with smooth to rough gray bark. Branches are brittle at the base and may take root if broken off.


The spike elongates some as fruit matures, the fruit becoming more loosely arranged than the flowers. Fruit is a capsule 3.5 to 6.5 mm long, yellowish when mature, covered in short, silky hairs, inflated at the base with a long, straight to slightly curved beak. The capsule splits into two halves when mature, releasing the cottony seed


There are over 20 species of Willows in Minnesota Satiny Willow is a large shrub or occasionally a small tree, primarily found on sandy or rocky lake shores and stream and river banks. It is very rare in Minnesota, where it reaches the southern fringe of its range in the arrowhead region of the state. According to the DNR, the first record is from 1886 at Lake Vermilion in St. Louis County and only 4 known locations existed when it was listed as Special Concern in 1996. Targeted biological surveys have since found only 8 more populations, most of which are along an 8-mile stretch of the Cloquet River. Its habitat is at risk from human activities and natural disasters a single weather event or development project could conceivably destroy a large portion of this species' presence in the state. It was elevated to Threatened in 2013. It is currently listed as Endangered in Wisconsin.

It is a fairly distinct species, recognized by the hairless twigs usually having a whitish waxy bloom narrow leaves that are toothless, typically rolled under along the edges (revolute), and have silky, mostly straight, white hairs on the underside fruit 3.5 to 6.5 mm long covered in short, silky hairs. It is not likely to be found in swamps, marshes or bogs. The leaves are very similar to Sage-leaved Willow (Salix candida), which is a low shrub usually under 3 feet tall with hairy stems, prominent stipules, and leaves and fruits that are woolly-hairy (tangled, matted hairs). Satiny Willow is known to hybridize with several other willows but none have been recorded in Minnesota.


The Southern Ocean is believed to play a key role in the global carbon cycle and millennial-scale variations in atmospheric CO2 (CO2,atm), which in turn may amplify the impacts of longer-term external climate forcing on global climate 1 . This role stems from the unique control the Southern Ocean is thought to exert on ocean–atmosphere CO2 exchange 1,2,3 by both facilitating the upward transport of nutrient- and CO2-rich water masses along outcropping density surfaces and their exposure to the atmosphere, and modulating the export of biologically fixed carbon into the ocean interior, where it is remineralized and may be effectively isolated from the atmosphere. It has been proposed that these two key aspects of the Southern Ocean’s role in the marine carbon cycle may have exerted a dominant control on past CO2,atm change, for instance via variations of dust-driven biological carbon fixation in the sub-Antarctic 4 , the extent of circum-Antarctic sea ice 5 impeding effective air–sea gas equilibration 6 , and/or changes in the strength or position of southern hemisphere westerlies driving the residual overturning circulation in the Southern Ocean 7,8 .

While all of these mechanisms for past CO2,atm change are compelling, observational evidence that might constrain the extent to which they have operated, in particular the balance of biological versus physical (that is, air–sea gas exchange or ocean dynamical) impacts, remains ambiguous. In the sub-Antarctic Atlantic north of the Polar Front (PF), decreased biological export production, along with a diminished aeolian supply of dust (and by inference iron) to the surface ocean, has been found to parallel millennial-scale increases in CO2,atm. These observations suggest a significant impact of dust-driven variations of the strength of the ‘organic carbon pump’ on CO2,atm (refs 9, 10, 11, 12). However, marked increases in CO2,atm are also accompanied by enhanced export productivity south of the PF (ref. 7). Polar- and sub-polar Southern Ocean export productivity changes thus appear to have opposed each other, raising questions concerning the overall magnitude and sign of the impact of Southern Ocean ‘organic carbon pump’ on CO2,atm, when integrated across both regions 11,13 . On the other hand, while 14 C evidence has provided direct support for a link between Southern Ocean carbon sequestration (and millennial-scale CO2,atm variability) and physical/dynamical controls on air–sea CO2 exchange 14 , these data remain sparse and only extend across the last deglaciation.

Here we present sub-millennially resolved qualitative and quantitative proxy reconstructions of bottom-water [O2] from sub-Antarctic Atlantic sediment core MD07-3076Q (14°13.7′W, 44°9.2′S, 3,770 m water depth Fig. 1) to estimate the apparent oxygen utilization (AOU) in deep waters, which is closely (stoichiometrically) related to the amount of remineralized dissolved inorganic carbon (DIC) because of the consumption of oxygen during the degradation of organic carbon. We use two independent proxy approaches: first, we determined the redox-sensitive enrichment of uranium and manganese in authigenic foraminifer coatings 15 , and second, we measured the difference in carbon isotopic composition between pore waters at the zero-oxygen boundary and overlying bottom waters, which is assumed to be reflected in δ 13 C of the benthic foraminifer Globobulimina affinis and Cibicides kullenbergi, respectively (Δδ 13 CC. kullenbergi–G. affinis refs 16, 17). Our deep sub-Antarctic Atlantic [O2] reconstructions show a close correlation to CO2,atm variations during the last deglacial- and glacial periods. The combination of our [O2] reconstructions with analyses of 230 Th-normalized opal fluxes, an indicator of biological export production 7,18 , and deep water 14 C ventilation ages, along with a robust age model for our study core 14,19,20 (Methods), highlights that carbon sequestration changes in the southern high latitudes cannot be attributed solely to changes in local biological export production. Instead, they involve significant changes in Southern Ocean vertical mixing and air–sea gas exchange, having direct implications for millennial-scale CO2,atm variations, since 65,000 years before present (BP).

DIC levels (shaded) and [O2] (contours, in μmol kg −1 ) 33,63 in (a) Southern Ocean- and Atlantic Ocean bottom waters and (b) in a meridional transect across the Atlantic (averaged between 70°W and 20°E). Hatched area broadly represents the region, where the deep DIC reservoir directly ‘communicates’ with the surface ocean and the atmosphere along steep density surfaces (equivalent to the area of strong positive CO2 fluxes across the air–sea interface in austral winter in the Southern Ocean 64 ), which is unique in the global ocean today. White circles show study cores and open symbols mark the location of ice cores that document past changes in atmospheric CO2 (CO2,atm as in Figs 2 and 3). Thick lines show the modern positions of the PF, the sub-Antarctic Front (SAF) and the sub-Tropical Front (STF) (south to north) 65 . Arrows show general pathways of North Atlantic Deep Water (NADW), AABW (Antarctic Bottom Water), CDW (Circumpolar Deep Water) and Antarctic Intermediate Water (AAIW).

2 Material and Methods

2.1 Taxa sampling

In the HDM, 16 sections containing

95 species of the Chamaetia-Vetrix clade are reported. Nine sections and more than half of the species are endemic or subendemic to this region. To cover the taxonomic species diversity in the HDM, we selected species to act as representatives of all nine endemic or subendemic sections in the HDM and adjacent areas (i.e., QTP, the Himalayas, Qinling Mountains, and other parts of the southern China mainland Tables S1, S2) (Fang et al., 1999 ). We also attempted to cover: (i) the morphological diversity of the group, sampling trees (e.g., Salix phanera), shrubs (e.g., S. oritrepha), and dwarf shrubs (e.g., S. lindleyana Wall. ex Andersson) and (ii) the distribution across altitudinal gradients (ranging from 570 m to 5200 m a.s.l.) inhabited by willows in the HDM and adjacent areas. Based on these initial considerations, we sampled 15 species of the Salix Vetrix-Chamaetia clade from the HDM and Nepal, each represented by one to four individuals, resulting in 46 accessions. Leaves of each sample were dried in silica gel. Voucher specimens collected for the present study are deposited in three herbaria: College of Forestry of Fujian Agriculture and Forestry University (FJFC), University of Goettingen (GOET), and University of Vienna (WU) (herbarium acronyms follow Thiers, 2020 ). Furthermore, 12 accessions of five widespread Chinese species, two of which (with six accessions) were published in Wagner et al. ( 2019 ), were included to cover five widely distributed non-endemic sections occurring in the HDM and adjacent areas. Finally, seven Eurasian Salix species (14 accessions) were published in Wagner et al. ( 2018 ) that represent the main Eurasian genetic clades these were also included in this study to examine the overall position of the HDM species in Salix phylogeny. Salix triandra L. was used as an outgroup following Wagner et al. ( 2018 ). Source details of all 72 individuals representing 27 species are provided in Table S1.

2.2 Ploidy determination

The ploidy level of 47 samples was measured by flow cytometry, with a species of known ploidy (S. caprea 2x = 2n =38) used as an external standard. The flow cytometry protocol of Suda & Trávníček ( 2006 ) was used for the dried leaf material. Silica gel-dried leaf materials (

1 cm 2 of each sample) were incubated for 80 min in 1 mL Otto I buffer (0.1 M citric acid, 0.5% Tween-20) at 4 °C, and then chopped with a razor blade. After incubating for 10 min on ice, the homogenate was filtered through a 30 µm nylon mesh. The suspension was centrifuged at 12.5 g at 10 °C for 5 min in a centrifuge (Heraeus Fresco 17 centrifuge Thermo Eletron LED, Osterode, Germany) this was repeated two to three times for some samples, until a pellet of nuclei showed up. The supernatant was discarded, and the nuclei were resuspended with 200 μL Otto I buffer. Before the samples were analyzed, 800 μL Otto II (0.4 M Na2HPO4.12H2O) containing 4′-6-diamidino-2-phenylindole (3 μg mL −1 ) was added and incubated for 30 min in the dark to stain the nuclei. DNA content measurements were done in a flow cytometer (CyFlow Space Sysmex Partec, Münster, Germany), and FloMax version 2.0 (Sysmex Partec) was used to evaluate the histograms for each sample.

The ploidy level was calculated as: sample ploidy = reference ploidy × mean position of the sample peak/mean position of reference peak. The quality of the measurements was evaluated by calculating coefficients of variation the range of coefficients of variation varied between 5% and 11% (Table S1). Coefficients of variation values higher than 5% could be caused by the polyphenols of willow leaves and the use of dried samples (Doležel et al., 2007 ). To confirm our results, we compared our DNA content measurements with previously known chromosome counts of S. magnifica and S. psilostigma. The results were congruent (i.e., 2x = 2n =38 for both species Wilkinson, 1944 Fang et al., 1999 ).

2.3 DNA extraction and RAD sequencing

The total genomic DNA for all 52 samples was extracted from silica gel-dried leaves using the Qiagen DNeasy Plant Mini Kit (Qiagen, Valencia, CA, USA) following the manufacturer's instructions. DNA quality and concentration were verified and quantified using a NanoDrop 2000 (Thermo Fisher Scientific, CA, USA), and Qubit measurements in the Qubit 3.0 Fluorometer (Life Technologies Holdings, Singapore, Malaysia). The quantified DNA was sent to Floragenex (Portland, OR, USA). Restriction site-associated DNA sequencing library preparation and sequencing were undertaken as described in Wagner et al. ( 2018 ), following the method of Baird et al. ( 2008 ). The DNA was digested with PstI, and sequenced on an Illumina HiSeq 2500 (Illumina, San Diego, CA, USA).

2.4 Restriction site-associated DNA sequencing data analysis

The raw sequence reads for all 52 samples were demultiplexed using I pyrad version 0.6.15 (Eaton & Overcast, 2017 ). After the quality check by using FastQC version 0.10.1 (Andrews, 2010 ), the 52 demultiplexed FastQ files were analyzed in combination with the published 14 European and six Chinese accessions using the I pyrad pipeline, with settings described in Wagner et al. ( 2018 ). Super-matrices for phylogenetic analyses were generated from three different thresholds of the minimum number of samples per locus, that is, m15 (loci shared by at least 15 samples), m25, and m40. Furthermore, for divergence time estimation, biogeographic analysis, and ancestral character evolution analyses, a reduced dataset was generated using one accession per species, resulting in 27 samples with an I pyrad threshold of m15.

2.5 Phylogenetic inference of species relationships

Phylogenetic relationships were inferred by a maximum likelihood (ML) approach using RaxML version 8.2.4 (Stamatakis, 2014 ). Support values for each node were calculated using 100 rapid bootstrap replicates (-f a option) based on the GTR + GAMMA nucleotide substitution model.

Additionally, we used ExaBayes version 1.5 (Aberer et al., 2014 ) to undertake Bayesian analyses. Four independent runs were executed with three heated chains for 1 000 000 generations with sampling every 1000 generations. The first 20% of all samples were discarded as burn-in. Tracer version 1.7.1 (Rambaut et al., 2018 ) was used to check the effective sampling size values (>200) for all estimated parameters for convergence. The tools postProcParam and sdsf included in the ExaBayes package were used to calculate the potential scale reduction factor (close to 1) and the average standard deviation of split frequencies (less than 0.01). Finally, a consensus tree was generated by using the “consense” tool of the ExaBayes package. FigTree version 1.4.3 (Rambaut, 2014 ) was used to obtain all trees.

2.6 Divergence time estimation

To estimate divergence dates, we used Beast version 1.75 (Drummond et al., 2012 ) with the reduced m15 dataset. The Bayesian uncorrelated log-normal strict molecular clock approach was applied using a GTR + Γ + I substitution model with four rate categories and a Yule model prior on speciation. Given the thousands of concatenated RAD loci as input data, we assumed a common mutation rate across the genome (see Cavender-Bares et al., 2015 ). Posterior distributions of parameters were estimated using two independent Markov chain Monte Carlo analyses of 10 000 000 generations with a 10% burn-in. Beast log files were analyzed with Tracer version 1.7.1 to assess convergence, and the combined tree files were used to generate a maximum clade credibility tree with median heights in TreeAnnotator version 1.7.5. The oldest reliable fossil determined as a member of subgenus Vetrix is known from Alaska and originated in the late Oligocene (Collinson, 1992 ). We calibrated the tree using this fossil, following Wu et al. ( 2015 ): the Chamaetia-Vetrix clade was assigned an exponential distribution prior with a mean of 1 and offset (hard bound constraint) of 23 Ma.

2.7 Ancestral character, altitudinal, and ancestral area reconstruction

We scored five morphological characters: (i) habit (ii) relative time of flowering and emergence of leaves (iii) catkin peduncle leaf type (iv) staminate catkin shape and (v) male flower abaxial nectary presence. We also scored altitudinal distribution. Data for all 27 included species were scored using floras (Rechinger, 1993 Fang et al., 1999 Ohashi, 2006 Argus, 2010 ), monographs (Martini & Paiero, 1988 Skvortsov, 1999 Argus, 2009 Hörandl et al., 2012 ), and through examination of herbarium material. Character state definitions and scorings are presented in Table S3. We used a parsimony unordered model to reconstruct ancestral states in Mesquite 3.51 (Maddison & Maddison, 2018 ) based on the ML tree of the m15 reduced dataset.

The extant distribution of all 27 species, the subregions of HDM sensu Zhang et al. ( 2009 ), and the mountain systems were used to define biogeographic regions. Five regions were considered: A, eastern Himalaya, Khasi and Jaintia Hills, Naga Hills, and southeast QTP B, north HDM, east QTP, and west Sichuan Basin C, south HDM, Yungui Plateau, and south Sichuan Basin D, Helan Mountains, Liupan Mountains, Qinling Mountains, Daba Mountains, Wu Mountains, Wuling Mountains, and east Sichuan Basin and E, other parts of Asia, Europe, North Africa, and North America (Fig. 1). The distribution ranges (Table S4) of the species are based on data from the Chinese Virtual Herbarium (CVH,, Global Biodiversity Information Facility (GBIF,, examinations of specimens label information, and relevant published works (Wang et al., 1993 Fang et al., 1999 Skvortsov, 1999 Argus, 2010 ).

Ancestral areas were reconstructed using BioGeoB ears (Matzke, 2014 ) in R version 3.5.1 (R Core Team, 2018 ). We tested three likelihood models, dispersal–extinction–cladogenesis (DEC), DIVALIKE, and BAYAREALIKE using the BioGeo Bears package, using the Akaike information criteria to select the optimal model. We then calculated the probabilities of the ancestral states based on the dated tree, selecting the model that received the best Akaike information criteria score (Table S5).

2.8 Niche modelling

We obtained and selected 114 localities with precise records of HDM clade species from the CVH, GBIF, and specimens deposited in the Beijing Forestry University herbarium (BJFC, collected by the first author), and annotated records of the included samples (Table S6). The records are evenly distributed over the species from the HDM and adjacent regions. To ensure correct species identifications of these distribution sites, we re-examined all available specimens or digital images of specimens for each record.

Nineteen bioclimatic variables for the present day and LGM (CCSM), at a 2.5-arc-min resolution, were downloaded from the WorldClim database ( (Hijmans et al., 2005 ). We calculated Pearson correlation coefficients (R) for all pairs of bioclimatic variables, and used absolute value of R <0.9 to remove highly correlated variables. Finally, we obtained 12 bioclimatic variables (Table S7). We used maxent version 3.4.1 (Phillips et al., 2018 ) to predict the current and LGM distributions of subclades I and II. The maxent analyses were carried out using 15 replicates each. The performance of each model prediction was tested by calculating the area under the receiver operating characteristic curve (AUC) (Phillips & Dudík, 2008 ). All distribution maps were visualized using ArcGis 10.6.1 (ESRI, CA, USA).

What controls the southern range of willows? - Biology

Inyo California towhee

The primary threat to the towhee has been the destruction of its habitat by cattle, feral horses and burros, off-road vehicles, campers, and hikers [1]. All of these threats have been substantially reduced since the species was placed on the federal endangered species list in 1987 (see below). Fire has recently become a localized threat, but magnitude of its impact is unknown [10].

The Inyo California towhee is believed to have been relatively stable (100-200 birds) between 1978 and 1987 [1, 3, 4] and between 1992 and 1995 (about 200 birds) [1]. A comprehensive 1998 survey located 640 adult [5]. Of birds on public lands, 72% were on NAWS, 25% on BLM, and 2% on state lands [2]. A survey of BLM and state lands in 2004 documented 204 adults and estimated a range-wide population of 725 adults [2]. Sites surveyed in 1998 and 2004 increased by an average of 13.6%. The increase was attributed in part to the reduction of feral burros and horses numbers [2]. Over 11,600 burros and 2,400 horses were removed from the Argus and Coso ranges since 1980, improving riparian and upland vegetative conditions [2]. A legal agreement in 2001 required further reductions of feral equines, off-road vehicles, camping, and other impacts on specific towhee habitats on BLM lands [6]. An August 2005 fire on NAWS impacted some riparian habitat, as did a 2005 flash flood in Mountain Springs Canyon, but the extent of habitat damage its impact on the towhee is not known [10].

While the population increased between 1998 and 2004, the range contracted, probably due to drier conditions reducing the suitability of marginal habitats [2]. The towhee appears to expand into marginal breeding habitats during wet years and contract to core riparian habitats in drier years. The appearance of singing birds in the Panamint Mountains 20 km to the east of the Argus Range suggests the towhee may be colonizing ranges beyond that historically known, and may be capabable of recolonizing the Coso Range 20 km to the west as well [2]. Comprehensive surveying of this ranges has been recommended [2].

What controls the southern range of willows? - Biology

Willow oak (Quercus phellos), also known as peach oak, pin oak, and swamp chestnut oak, grows on a variety of moist alluvial soils, commonly on lands along water courses.

This medium to large southern oak with willowlike foliage is known for its rapid growth and long life. It is an important source of lumber and pulp, as well as an important species to wildlife because of heavy annual acorn production. It is also a favored shade tree, easily transplanted and used widely in urban areas.


Native Range

Willow oak is found mainly in bottom lands of the Coastal Plain from New Jersey and southeastern Pennsylvania south to Georgia and northern Florida west to eastern Texas and north in the Mississippi Valley to southeastern Oklahoma, Arkansas, southeastern Missouri, southern Illinois, southern Kentucky, and western Tennessee (14).

-The native range of willow oak.


The climate in which willow oak grows is humid and temperate, characterized by long, hot summers and mild, short winters. It grows mainly in the zone where daily normal temperatures are above 0° C (32° F). Frost-free days number 180 to 190 in the north-northeastern range and 300 in the south-southwestern range (29). Average summer temperatures vary from 21° to 27° C (70° to 80° F), with extremes of 38° to 46° C (100° to 115° F). Average winter temperatures range from -4° to 13° C (25° to 55° F) with extremes to -29° C (-20° F). Average annual temperatures throughout the range are 10° to 21° C (50° to 70° F).

Across the entire range, surface winds in the summer are off the Gulf of Mexico and winter winds are variable. Normally there are about 2,700 hours of sunshine annually in willow oak's range. Relative humidity at noon ranges from 60 to 70 percent in January and 50 to 70 percent in July.

Annual precipitation varies from 1020 to 1520 mm (40 to 60 in) and is fairly evenly distributed throughout the year there is slightly more precipitation in the summer in the southeastern portion of the range. Greatest precipitation is in the central Gulf area. Average annual snowfall varies from 0 to 127 cm (0 to 50 in) over the range. The normal number of days with snow cover of at least 2.5 cm (1 in) varies from 0 to 40.

Soils and Topography

Willow oak grows on a variety of alluvial soils and is found on ridges and high flats on first bottoms of major streams. On second bottoms it grows on ridges, flats, and sloughs and can be very common in some minor stream bottoms. It develops best on clay loam ridges of new alluvium. Studies show that site quality of willow oak decreases from the higher to the lower topographic positions within a floodplain.

Willow oak is rarely found on upland sites but is occasionally seen on hardpan areas of very old terraces and on hammocks or bays. Trees on these sites are usually of poor quality.

In addition to topography, willow oak quality and growth rate are affected by soil characteristics and available moisture. In the Mississippi Delta, site quality decreases within each topographic position as clay content 30 to 46 cm (12 to 18 in) below the soil surface increases. For the non-Delta region in the South, site quality decreases within a topographic position as available potassium in the top 15 cm (6 in) of soil increases (26).

The best soils for willow oak growth are those that are deep (more than 1.2 in or 4 ft), without a pan, and relatively undisturbed (1). They are medium textured, silty or loamy, with no compaction in the surface for 30 cm (12 in) and are granular in the rooting zone below.

In contrast, the worst soils are shallow, have an inherent pan, or have been intensively cultivated for more than 20 years. They are fine textured, clayey, with a strongly compacted surface for 30 cm (12 in) and have a massive structure in the rooting zone.

Moisture must be readily available in the soil during the growing season for best willow oak growth. The ideal water table depth is 0.6 to 1.8 in (2 to 6 ft), while depths less than 0.3 in (I ft) and greater than 3 m (10 ft) are unsuitable. Radial growth is not affected by standing water during the growing season (February to July) (4) but is greatly increased if the water table is artificially raised by impoundments to within 1.2 in (4 ft) of the soil surface (5).

For best growth, the topsoil should be at least 15 cm (6 in) deep, with more than 2 percent organic matter. Optimally, soil pH in the rooting zone should be 4.5 to 5.5. The site quality worsens as the topsoil becomes more shallow, organic matter decreases, and pH departs from optimum. The soils on which willow oak is most commonly found are in the orders Inceptisols and Alfisols.

Associated Forest Cover

Willow oak is an important tree in the forest cover types Willow Oak-Water Oak-Diamondleaf Oak (Society of American Foresters Type 88) and Sweetgum-Willow Oak (Type 92). It is also a minor associate in Loblolly Pine-Hardwood (Type 82), Swamp Chestnut Oak-Cherrybark Oak (Type 91), Sugarberry-American Elm-Green Ash (Type 93), and Overcup Oak-Water Hickory (Type 96) (22). Other trees associated with willow oak are water oak (Quercus nigra), red maple (Acer rubrum), cedar elm (Ulmus crassifolia), eastern cottonwood (Populus deltoides), honeylocust (Gleditsia triacanthos), and persimmon (Diospyros uirginiana).

Swamp-privet (Forestiera acuminata), roughleaf dogwood (Cornus drummondii), hawthorn (Crataegus spp.), and American hornbeam (Carpinus caroliniana) are major shrub or small tree associates.

Life History

Reproduction and Early Growth

Flowering and Fruiting- Willow oak is monoecious male and female flowers are in separate catkins on the same tree. Staminate flowers are in slender yellow-green hairy catkins, pistillate flowers are tiny, in few flowered clusters at junction of leaf stems. Flowering occurs from February to May, about a week before the leaf buds open.

Late freezes, after the flower and leaf buds have opened, kill the flowers and defoliate the trees. New leaves develop after the freeze, but a second crop of flowers is not produced.

Seed Production and Dissemination- Seed production starts when the tree is about 20 years old. The acorns are small, 10 to 15 mm (4 to 0.6 in) in length, about as broad as long, occurring solitary or in pairs (28). They mature between August and October of the second year after flowering. The first acorns to fall usually are not mature, as indicated by failure of the cup to detach easily. Good mature acorns are heavy and have a bright color with a brown micropylar end (3).

Good seed crops are produced nearly every year. Mature trees produce between 9 and 53 liters (0.25 to 1.5 bu) or about 5.2 to 31.3 kg (11.5 to 69 lb) of acorns per year. Since willow oak averages 603 seeds per liter (21.250/bu) (27), the number of seeds per tree ranges from about 5,400 to 31,900. Seeds are disseminated by animals and, in areas subject to overflow, by water.

Prolonged submersion of willow oak acorns reduces their germination ability slightly, but not enough to affect the species capability to regenerate an area (13).

The acorns can be stored under moist, cold conditions. For germination, acorn moisture content must not drop below 40 percent a 50 percent moisture content is preferable. Seeds should be stored at temperatures of 2° to 4° C (35° to 40° F) for 60 to 90 days before planting.

Seedling Development- Seeds germinate the spring following seedfall. Germination is hypogeal (27). The best seedbed is a moist, well-aerated soil with an inch or more of leaf litter. Early height growth is moderate on good sites in the southern part of the range, seedlings average 1.4 in (4.5 ft) in 2 years.

Willow oak normally reproduces as a single tree or in very small groups. Reproduction occurs in small to large openings created either naturally or as a result of logging. Successful regeneration usually is the result of the presence of advance regeneration before the stand is disturbed. If willow oak regeneration does not exist on the ground before disturbance, there is little chance that successful regeneration of this species will occur. Seedlings are very intolerant of saturated soil conditions except during the dormant season, when they can tolerate complete submergence without appreciable mortality. After spring foliation, complete submergence longer than 5 to 7 days can be fatal, but seedling mortality usually does not occur unless saturation periods exceed 60 days (10). During saturation periods, some secondary roots are killed and no adventitious shoots are formed, height growth essentially halts. After the saturation period ends, growth of roots and shoots resumes.

Although willow oak exhibits only medium tolerance to shade, seedlings may persist for as long as 30 years under a forest canopy. They continually die back and resprout. As a result they may become misshapen. These seedling-sprouts respond to release (12).

Vegetative Reproduction- Willow oak readily sprouts from stumps of small trees. Sprouts from advance reproduction are a principal method of natural regeneration. Larger diameter stumps do not sprout readily.

Cuttings taken from young parent trees can be propagated if treated with indoleacetic acid success decreases with increasing age of the parent tree. Untreated cuttings fail completely. Layering and budding are not effective as a means of vegetative reproduction.

Sapling and Pole Stages to Maturity

Growth and Yield- Willow oak is medium size to large, attaining 24 to 37 m (80 to 120 ft) in height and commonly 100 cm (39.5 in) in d.b.h. On good sites it makes moderately rapid growth. Diameter growth is dependent upon tree size. In unmanaged stands on good sites, trees 15 to 30 cm (6 to 12 in) in d.b.h. averaged 6.6 cm (2.6 in) diameter growth in 10 years (18). In the 36 to 46 cm (14 to 18 in) class, they grew 7.9 cm (3.1 in) in 10 years in the 51 to 71 cm (20 to 28 in) class, 7.1 cm (2.8 in). Dominant crop trees in a well-stocked managed stand probably average 8.9 to 10.2 cm (3.5 to 4.0 in) in d.b.h. growth in 10 years, with a maximum of 15.2 cm (6 in) (7,26).

Willow oak commonly exists as a major component in mixed bottom-land stands. In a fairly typical stand near Stoneville, MS, willow oak basal area averages 7.1 m²/ha (31 ft³/acre) out of a total of 21.1 m²/ha (92.0 ft²/acre) (19). The same willow oak component of the stand averages 57 273 kg/ha (51,100 lb/acre) of total dry fiber, 64 percent of which is contained in the bole 87 percent of the total is contained in trees larger than 43.2 cm (17 in).

Willow oak has been successfully planted in stream bottoms or branch heads. After 17 years, trees averaged 10.9 cm (4.3 in) in d.b.h. and 14 m (46 ft) in height (6).

Rooting Habit- Where it occurs on alluvial soils, willow oak feeder roots are concentrated in the aerated layer above free water. Here they form extensive ectomycorrhizal associations that aid the tree in taking up nutrients and water and offer some protection against root diseases. Roots do not penetrate into the zone of free-standing water. In the soil region of best growth, root growth usually begins during early March.

Since complete soil saturation during the growing season inhibits root growth of seedlings, it probably has the same effect on mature trees. Production of ectomycorrhizae also is inhibited under saturated soil conditions, but once the excess soil moisture in the upper root zone dissipates, both root and mycorrhizae growth resume (9). Permanent standing water, however, kills the root system and ultimately the tree.

Reaction to Competition- A straight, tall, slender trunk is common. Not a rapid pruner on good sites, it is a very ineffective natural pruner on poor sites.

A tendency exists for the production of epicormic branches if the dormant buds along the main stem are stimulated to grow by some disturbance. Among the causal disturbances are breakage of the tree crown, wounding of the stem, drought, flooding, suppression, and unsuitable sites (16). Release stimulates epicormic branching on intermediate or suppressed trees, but dominant or codominant trees are much less susceptible. Thinning should aim at releasing undamaged trees pole size and larger that occupy dominant and codominant positions.

Although slow to heal from artificial pruning, live-branch wounds initially heal more rapidly than dead-branch wounds, but up to 4 years are required for healing more than 96 percent of either kind of wound (11).

Willow oak is a subclimax species and is classed as intolerant of shade. All trees, except those of poor vigor, respond well to release.

Damaging Agents- Squirrels, birds, and insects (mainly acorn weevils) reduce the fruit crop, as do hogs.

A principal enemy of willow oak is fire. Seedlings and saplings are killed by even a light burn hot fires kill larger trees. Trees not immediately killed by the fire are often wounded and become susceptible to butt rot fungi.

A common canker on bottom-land willow oaks is caused by Polyporus hispidus (25). This insidious fungus grows rapidly, cankers lengthening 10 to 15 cm (4 to 6 in) per year, and may cause as much as 25 percent cull in some areas. Cankered trees should be removed as soon as possible, both to salvage the log and to remove the tree as a source of infection (15).

Perhaps the most serious insect pests are the trunk borers. They cause serious degrade in saw log quality. Three of the more common are the red oak borer (Enaphalodes rufulus), carpenterworm (Prionoxystus robiniae), and living-beech borer (Goes pulverulentus) (23,24).

Willow oak has been shown to be susceptible to acid rain, the foliage showing yellow or brown necrotic zones when exposed to simulated rain of less than 3.2 pH (20).

Special Uses

Since it produces an acorn crop almost every year, willow oak is an important species for wildlife food production. In addition to being a major supplier of food for game animals such as ducks, squirrels, deer, and turkey, willow oak supplies many other animals. Blue jays and red-headed woodpeckers are major consumers, while grackles, flickers, mice, and flying squirrels utilize the tree itself (8).

A favored shade tree, it is widely planted as an ornamental. It is also a good species to plant along margins of fluctuating-level reservoirs (21). Willow oak can be harvested when quite young and utilized as biomass (17). Pulp yields per unit volume of young versus old trees do not differ greatly and chemical demand in pulping is not greatly increased (2).

Willow oak is being utilized in hardwood plantations, since it gives a good combination of pulping characteristics and growth rate.


No racial variations of willow oak are known, but the following hybrids are recognized (14): Quercus phellos x nigra (Q. x capesii W. Wolf) Q. phellos X velutina (Q. x filialis Little) Q. phellos x ilicifolia (Q. x giffordii Trel.) Q. phellos x rubra (Q. heterophylla Michx. Q Q. phellos x falcata (Q. x ludoviciana Sarg.) Q. phellos x shumardii (Q. x moultonensis Ashe) Q. phellos x marilandica (Q. rudkinii Britton) Q. phellos x palustris (Q. x schociana Dieck.).

Life History

Flowering and Fruiting

Black willow is dioecious. No consistently reliable morphological characteristics are associated with the identification of the sexes. Male and female are indistinguishable except during flowering and seed development. In natural stands the sex ratio is probably 1 to 1, as has been determined for other dioecious tree species, including members of Salicaceae. Flowering begins in February in the southern portion of the range and extends through late June at the northern limits. The many-flowered catkins usually appear at the time of or immediately preceding leafing out. Pollination is mainly by insects the flowers contain nectar. Pollen is also carried by winds. The seed ripens quickly 45 to 60 days after pollination the small (3 to 6 mm or 0.12 to 0.24 in) light-brown capsules begin to split open and shed minute green seeds that have a hairy covering.

Vegetative Reproduction

Root stocks of very young willow trees sprout prolifically. Propagation by cuttings is the usual method of artificial regeneration. With adequate moisture, good cuttings, and sufficient cultivation to reduce competition from other vegetation, first-year plantation survival can be close to 100 percent. Post-size willow cuttings have been rooted for use in flood projects to prevent gullies (4).

Wild radish biology and management

Wild radish is of Mediterranean origin and is a major weed of winter crops in southern Australia (Murphy et al. 1999). The major source of spread is due to contamination in grain, chaff and hay. It is highly competitive in crops and can cause a yield loss of 10%-90% in cereals, canola and pulses (Storrie, 2014). It germinates in a wide range of temperatures from 5°C to over 35°C, with optimal diurnal fluctuation of 25°C/10°C. Wild radish can therefore emerge at any time of the year given sufficient soil moisture. However, wild radish predominantly emerges in late autumn (May) and early winter, followed by staggered emergence throughout the season (Young, 2001). Deeper burial depths often result in decreased emergence but at the expense of increased persistence. Strong dormancy and long persistence are the two most important features contributing to the difficulty in control. Fresh seeds of wild radish are dormant and many seeds will not germinate until the second season after their formation (about 18 months later) (Storrie, 2014). Wild radish seed has a longevity of more than six years. Two critical steps are required to effectively manage wild radish: (1) prevent seed return to the seedbank (seedset control) and (2) deplete the existing seedbank (through emergence and seed decay).

Without the new addition of fresh seeds, control measures have to be in place for more than six years in order to exhaust the seedbank (Cheam, 1996), which is supported by results from a long-term rotation trial established in Wagga Wagga, i.e. 2013 field peas &rarr 2014 barley &rarr 2015 triazine tolerant (TT) canola &rarr 2016 wheat &rarr 2017 barley &rarr 2018 wheat.

Over the six year period, the management (Mgt) 1 (treatment pre-emergent (PRE)) had much higher wild radish seeds in the seedbank than Mgt 2 (treatment PRE + post-emergent (POST)) and Mgt 3 (treatment PRE + POST + Seedset) (Figure 1). Mgt 2 and 3 were equally effective, resulting in a rapid decline of wild radish seedbank in the first year, followed by a steady decline over the remaining years. The results indicate that the wild radish seeds persist well in the soil, requiring a long-term approach of more than six years to manage the wild radish problem. Any new seed replenishment will waste the previous management efforts.

Figure 1. Seedbank dynamics of wild radish between 2013 and 2018 under three management options. Mgt 1&ndash Pre-emergent treatments only (PRE), Mgt 2 &ndash PRE followed by post-emergent treatments (PRE + POST), and Mgt 3 &ndash (PRE + POST) followed by late seedset control (Seedset).

Herbicides are a valuable tool for wild radish control. For effective control, it is necessary to target young and actively-growing weeds with a rosette of less than 5cm in diameter. A two-spray herbicide strategy is recommended for high levels of in-crop control (Storrie, 2014). The &lsquotwo-spray&rsquo strategy on wild radish was also evaluated in two field trials in southern NSW (Wagga Wagga and Marrar, 2015).

The field had a natural infestation of wild radish at 110 plants/m 2 and 78 plants/m 2 at Wagga Wagga and Marrar sites, respectively. A pre-sowing double-knockdown with glyphosate followed by paraquat was used to control the emerged wild radish. Wheat (cv. Corack) was sowed at Wagga Wagga site on 1 June 15 and oats (a mixture of cv. Yiddah and Mitika ) sowed at Marrar site on 9 May 2015.

The two-spray strategies were highly effective on wild radish control. The 1st spray of Bromicide® MA followed 40 days later by each of the fourteen 2nd spray treatments had 100% control of wild radish (Table 1). However, Bromicide® MA without a follow-up spray only achieved 85% control.

Without the first spray of Bromicide® MA, five 2nd spray treatments Amicide® 700, Jaguar®, Broadside®, Bromicide® MA and a mixture of ParadigmTM + LVE Polo 570 (LVE MCPA) gave poor control of wild radish (<90%). Bromicide® MA applied on 16 September had only 30% control of wild radish as compared to the same treatment applied on 7 August (85%).

Table 1. Two-spray strategy on wild radish control in wheat (Wagga Wagga 2015).

Special Issue in honour of Prof. van Staden’s 80th Birthday

E.E. Elgorashi , L.J. McGaw , in South African Journal of Botany , 2019

3.2 Lipoxygenase inhibitors

Leukotrienes represent another class of inflammatory mediators that are produced as a result of arachidonic acid metabolism by LOX enzymes ( Häfner et al., 2019 ). Leukotrienes have been reported to be responsible for the attachment of white blood cells to the endothelium of damaged blood vessels and act as chemoattractants for phagocytes ( Hong et al., 2019 ). Furthermore, clinical manifestations of pathological conditions such as asthma and anaphylaxis have been attributed to leukotriene production ( Sirois, 2019 ). The most actively investigated leukotrienes are those produced by 5-LOX present in inflammatory cells such as polymorphonuclear neutrophils, basophils, mast cells, eosinophils and macrophages ( Foegh et al., 1998 ).

Screening against LOX activity focused mostly on essential oils producing African plants. Southern Africa is home to about 26 Salvia species which are used to treat microbial infections, cancer and inflammation ( Kamatou et al., 2008, 2010 ). The in vitro anti-inflammatory activity of essential oils and solvent extracts of 16 Salvia species were evaluated using the 5-LOX assay ( Kamatou et al., 2005, 2007, 2008, 2010 ). The essential oils had better 5-LOX inhibitory effect when compared to the crude extracts with the IC50 values ranging between 22.81 and 77.32 μg/ml. With the exception of Salvia radula Benth., solvent extracts had low 5-LOX inhibitory effect with IC50 values being greater than 100 μg/ml ( Kamatou et al., 2005, 2007, 2008, 2010 ).

Medicinal plants of southern African origin have been used for the treatment of skin diseases for centuries. Some of these plants have been investigated for their potential anti-inflammatory activity using the 5-LOX assay ( Frum and Viljoen, 2006a, 2006b ). Among the plants screened, Croton sylvaticus Hochst., Melianthus comosus Vahl, Pentanisia prunelloides (Klotzsch) Walp. and Warburgia salutaris (G.Bertol.) Chiov. displayed promising 5-LOX inhibitory activity with IC50 values less than 61 ppm (Frum and Viljoen 2006a). Essential oil-bearing plants that are commonly used to treat dermatological pathologies such as Helichrysum odoratissimum (L.) Sweet, Heteropyxis natalensis Harv. and Lippia javanica (Burm.f.) Spreng. have also been investigated for their 5-LOX inhibitory activity (Frum and Viljoen 2006b). Their hydrodistilled essential oils displayed promising 5-LOX inhibitory activity with IC50 values between 35 and 75 ppm. β-Caryophyllene, 1,8-cineole and limonene are behind the activity. The study also revealed that the 5-LOX enzymatic reaction is stereospecific as enantiomers and racemic mixtures of limonene displayed significantly different 5-LOX inhibitory activity. Furthermore, the monoterpene 1,8-cineole appeared to cause partial potentiation of the anti-inflammatory activity displayed by limonene (Frum and Viljoen 2006).

Vitex is another essential oil-producing South African genus (Verbenaceae) that is reputed for its medicinal value ( Nyiligira et al., 2004 ). The genus has been reported to be used in traditional medicine to treat a wide range of pain-related ailments including asthma, allergy, wounds, skin diseases, snakebites and body pain ( Neuwinger, 2000 ). Both volatile and non-volatile extracts of five South African Vitex species were investigated for anti-inflammatory activity using the 5-LOX assay. All essential oils effectively inhibited the enzyme, with V. pooara Corbishley producing the most promising activity (IC50 = 25 ppm). However, all non-volatile extracts were found to be inactive at the starting concentration of 100 μg/ml ( Nyiligira et al., 2004, 2008 ). A number of South African Commiphora species (Burseraceae) have been investigated for anti-inflammatory activity using 5-LOX to validate their use in the treatment of inflammatory diseases ( Paraskeva et al., 2008 ). The stem extracts of these species exhibited moderate to good 5-LOX inhibitory activity. IC50 values ranged from 27.8 to 66.2, with Commiphora pyracanthoides Engl. displaying the greatest inhibitory activity with IC50 = 27.86 μg/ml ( Paraskeva et al., 2008 ).

In addition, essential oil bearing plants from Algeria namely Teucrium polium subsp. capitatum (L.) Briq., Origanum floribundum Munby ( Kerbouche et al., 2015 ) and Tetraclinis articulata (Vahl) Mast. ( Djouahri et al., 2015 ) from Burkina Faso such as Pterocarpus erinaceus Poir. ( Noufou et al., 2016 ) from Cameroon including Citrus reticulata var. Madagascar and C. sinensis var. Casagrande ( Dongmo et al., 2008 ) and from Madagascar namely Cedrelopsis grevei Baill. & Courchet ( Afoulous et al., 2013 ) have also been investigated for their LOX inhibitory activity.

Apart from the focus on members of specific genera or families, some research groups screened different plant species spanning a wide range of plant families. For instance, Adebayo and co-workers ( Adebayo et al., 2015 ) investigated 25 medicinal plant species belonging to 15 families used in the southern African region for the treatment of inflammation, pain, arthritis and stomach ailments for their 15-LOX inhibitory activity. Most plant extracts had modest inhibition against 15-LOX activity (IC50 < 100 μg/ml), however, extracts of two plants namely Peltophorum africanum Sond. and Zanthoxylum capense (Thunb.) had promising inhibitory activity against 15-LOX with IC50 of 12.4 and 14.9 μg/ml respectively ( Adebayo et al., 2015 ). Another example is the investigation of seven essential oils producing plants from Burkina Faso for their LOX-1B inhibitory activity. Essential oils from leaves of Ocimum basilicum L., Ocimum americanum L., Hyptis spicigera Lam., Lippia multiflora Moldenke, Ageratum conyzoides (L.) L., Eucalyptus camaldulensis Dehnh. and Zingiber officinale Roscoe inhibited LOX-B1 at a concentration of 8 mg/ml. Only Z. officinale showed inhibitory activity against the enzyme at 0.4 mg/ml ( Bayala et al. (2014) .

Mosquito Species in Mass.

There are 52 mosquito species found in Massachusetts some are common, and others are found less frequently. Each species has it's own unique combination of characteristics. The presence of a particular mosquito species is dependent on the type of nearby wetland or habitat. Examples of different habitats that produce different mosquito species include permanent swamps, temporary woodland pools, river flood plains, cattail swamps or artificial containers. The last item can be almost any container which can hold stagnant water for at least a week in the summer, including roadside highway drains, old rimless tires, unused swimming pools, uncovered empty trash cans, and bird baths.

The species of mosquito found at any one time in an area is dependent on temperature and season there are early spring, late spring, summer, and mid-summer species. Some mosquito species have several generations each summer, so their populations increase as the summer goes along. Most mosquito species are active primarily during dusk and dawn or during cloudy warm days. However, one local species is active all night and some species will bite during hot sunny days. Three of our local mosquito species will enter protected shelters such as houses, and it is usually one of these three species that annoy people while they are trying to sleep.

While some mosquitoes are indiscriminate about what they bite, most are selective. Some of our mosquito species feed primarily on humans and other mammals, while others mostly bite birds, and still others feed on amphibians (such as frogs) or reptiles (such as snakes). Some species are very aggressive and persistent, while others are very shy. Finally, some deliver a more annoying bite that results in more itching.

The chance of acquiring a mosquito-borne disease in Massachusetts is extremely rare. However, the species which are believed to transmit Eastern Equine Encephalitis include some of the most numerous species, which on given nights can be caught on any suburban or rural property in eastern or central Massachusetts. West Nile Virus has been introduced into our area in the year 2000, and continued research is showing many species of mosquito, including human biters, adept at carrying and possibly transmitting this disease. Mosquitoes also transmit animal diseases, and the probability of a pet dog or cat acquiring heartworm is not so remote. It is recommended that a veterinarian monitor your pet and administer the proper preventative medication.

Read the "Discovery of New Mosquito Species in Massachusetts" Press Release from July 16, 2000, regarding the Aedes japonicus japonicus mosquito species.

Mosquito ID cards produced by staff at CMMCP are available for certain species click on the underlined species name for a pictorial ID.

  1. Aedes albopictusAedes albopictus was first collected in the United States at a tire dump near Houston, TX in 1985. The species spread rapidly through the southern United States and has been documented in over 25 states over the last decade. The first record of this species in Mass. was documented in 2000. Aedes albopictus is a multi-voltine species and should have a seasonal distribution similar to that of Ochlerotatus triseriatus. Ae. albopictus is an opportunistic container breeder that is capable of utilizing natural as well as artificial container habitats. Although the mosquito is most often associated with discarded tires in this country, it has the ability to adapt to an exceptionally wide range of confined water sources. The mosquito is known for its ability to survive in very small collections of water, requiring only 1/4" of depth to complete its life cycle.
  2. Aedes cinereus — Common late spring and early summer mosquito pest of humans and other mammals. Larvae are found in late April and May in tussock and leather-leaf marshes. Aedes cinereus is a univoltine species that hatches in greatest numbers during the month of May. Egg hatch is staggered, however, and specimens can be collected well into the month of June. The species may reappear during the summer and relatively large populations can be found following heavy rains in August and September.
  3. Aedes vexans— Very common summer mosquito. This pest of humans and other mammals can have several generations each season, so the population may increase during the summer. Larvae are found in a wide variety of temporary pools and wetlands. This mosquito is a suspect in the transmission of EEE from birds to humans. After significant rain events, this mosquito can be quite numerous and is considered a major pest of man.
  4. Anopheles barberi — A tree hole habitat mosquito in eastern North America. The larvae are predators of other mosquito larvae. It has been shown to be a vector of malaria in the laboratory, but it is not thought to be an important malaria vector in the wild.
  5. Anopheles crucians — A mosquito that develops in semi-permanent and permanent pools, ponds, lakes and swamps. It may be a vector for malaria in certain areas.
  6. Anopheles earlei — Larvae are found in cold, clear water at the margins ponds and pools containing emergent and floating vegetation. They are also found in woodland pools, bogs, marshes and along sluggish streams. Females are dusk- and early-evening biters and will enter houses to bite.
  7. Anopheles punctipennis — Found occasionally in the spring and summer. This pest of humans and other mammals has a mildly annoying bite. The larvae are found in a wide variety of wetlands including permanent swamps and along the edges of ponds and slow moving streams.
  8. Anopheles quadrimaculatus — Common summer mosquito. A pest of humans and other mammals that readily enters houses and has a mildly annoying bite. The population increases during the summer. The larvae are found in clear water amongst low vegetation or floating debris, in permanent swamps, and along the edges of ponds and slow moving streams.
  9. Anopheles walkeri— The larvae of this species occur in fresh-water marshes containing emergent or floating vegetation. It is reported that cut-grass shaded by willows or button bushes off the most ideal larval habitat. Adults have been found resting in dark extremely moist situations, particularly around the shaded bases of cut-grass and other shore-line shrubbery.
  10. Coquillettidia perturbans — Very common mid-June to mid-August mosquito. An indiscriminate pest of birds, humans and other mammals that is known to be a vicious biter, and will readily enter homes. The larvae are unusual in that they are found attached to the submerged roots of cattails and a few other aquatic plants. This trait makes this species impervious to control using some pesticides that are effective against larvae of other species. This mosquito is suspected in the transmission of EEE from birds to humans.
  11. Culex erraticusCulex erraticus is a competent vector of Eastern equine encephalitis virus, and both St. Louis encephalitis virus and West Nile virus have been isolated from field-collected specimens. Previous bloodmeal analysis studies have shown this species to be a generalist, feeding on a variety of mammals, birds, reptiles, and amphibians. This behavior can bridge arboviral transmission across different vertebrate groups.
  12. Culex pipiens — Very common year round mosquito which primarily feeds on birds. It will readily enter a house, but is considered shy. It will typically only bite people when they are motionless, usually while they are sleeping. The larvae are found in water holding containers and in polluted waters. Culex pipiens are considered the primary vector of West Nile Virus.
  13. Culex restuansCulex restuans has a distribution that ranges from central Canada south into Mexico. The mosquito is very common in the eastern and central United States. Culex restuans undergoes a life cycle that is typical for domestic Culex. Inseminated adult females enter hibernation in fall and pass the winter in a period of quiescence. Culex restuans utilizes an exceptionally wide range of larval habitats. The water used by this species can vary from nearly clear to grossly polluted. Culex restuans regularly colonizes temporary ground pools that remain flooded after they have produced broods of floodwater Ochlerotatus. Culex restuans is also the first species to utilize water that collects in discarded tires. The species can often be found in tire water that is absolutely clear and devoid of leaf litter.
  14. Culex salinarius — Common summer mosquito. A fierce biting pest of birds, humans and other mammals which can have several generations in a summer, so the population may increase during the season. This mosquito is active all night. Larvae are found in both fresh and polluted grassy hummock areas of permanent water swamps. West Nile Virus has been isolated from this species in 2000.
  15. Culex territansCulex territans is quite common throughout most of eastern Europe and is even found in parts of Africa. In North America, Cx. territans extends from Alaska and Canada south through most of the United States. Culex territans has a life cycle that is typical for most Culex species. In late fall, inseminated adult females feed on carbohydrates and hibernate in subterranean enclosures where they pass the winter in a state of torpor. The mosquitoes emerge in very early spring, obtain a blood meal and lay the first egg rafts of the season. Culexterritansis a frog feeder and it is not uncommon to see this species feeding on Spring Peepers. Egg hatch, however, may be delayed because of the mosquito's unique oviposition habits. Unlike most Culex, Cx. territans females rarely deposit their egg rafts directly on the surface of the water. This mosquito normally positions the raft up on the bank and relies on rainfall or rising water levels to flush the eggs onto the water's surface. Culex territans shares habitat with many of the univoltine Ochlerotatus in early spring, a variety of Anopheles sp. later in the summer and Uranotaenia sapphirina very late in the season. The species is occasionally found in containers but cannot tolerate even moderate levels of pollution. Culexterritansis common in farm ponds, swamps and bogs and roadside ditches. Culexterritansis one of the few species that can be collected from streams. It is not uncommon to find larvae within the grassy margins of slow moving streams and specimens are sometimes found in rock pool habitats normally associated with Ochlerotatus atropalpus.
  16. Culiseta impatiens — Larvae are found in semi-permanent and shaded permanent ponds. Adults are widespread. Females overwinter as mated nullipars, and are one of the earliest emerging blood-feeders. Females are extremely long lived, surviving until late fall. Eggs are laid in rafts of about 100. There is only one generation per year. Males do not swarm, and mated pairs have been found on cave roofs. It is found throughout western and northeastern North America.
  17. Culiseta inornata — Larvae found in a wide range of habitats including marshes, seepages, ditches, canals ponds, etc. Larvae can tolerate water with a salinity up to 26 ppt. Biting activity on overcast days, dusk and at night. Flight range is less than five miles.
  18. Culiseta melanura— Common spring and summer mosquito. A bird- feeding mosquito that can have several generations per year, so the population may increase towards the end of the summer. Larvae are found in holes in the root structures of white cedar and red maple trees in swamps. This is an important mosquito species because it is believed to spread EEE virus through the bird population. This mosquito was not thought to be a mammal-biter, but recent research has shown a small percentage of it’s bloodmeals are taken from mammals.
  19. Culiseta minnesotae — Larvae are found in semi-permanent to permanent marshes. Females overwinter as mated nullipars, emerging in early May to feed. Eggs are laid in a raft on the water surface. Larvae hatch in mid to late May. Larvae often cluster below aquatic vegetation, often in association with Culiseta morsitans. Mating habits are unknown. Blood-seeking adults have been collected in late summer, and it is believed that the species is likely multivoltine. Females are blood feeders, preferring birds. Not known to bite man. In North America, found in across south-central Canada and the north-central states.
  20. Culiseta morsitansCuliseta morsitans is a mosquito of the northern United States with a distribution that extends through Canadian Yukon Territory into Alaska. The mosquito is fairly common in New England and upper New York state. Records from the Atlantic coast region indicate that the species has been collected as far south as Delaware. Culiseta morsitans has a life cycle similar to that of the northern Ochlerotatus group of mosquitoes. The species is considered univoltine but females are long lived and frequently appear in light trap collections well into the summer. Unlike most members of the Genus Culiseta, the egg rafts are deposited on damp earth, probably deep within the Carex tussocks that are so common in their breeding habitat. Mature stands of red maple that grow in 12-18" of early spring ground water provide typical habitat. Uprooted trees are common in many of the swamps that support this species and tussocks of Carex serve as indicators of the semi-permanent nature of the habitat.
  21. Ochlerotatus abserratus — Very common early spring to early summer mosquito pest of humans and other mammals. Larvae are found in temporary spring pools and margins of permanent waters in April. Readily bites in shaded areas during the day.
  22. Ochlerotatus atropalpus — Uncommon mosquito in Massachusetts, but can be a pest of man as our data has shown. This species is known as the "rockpool" mosquito, which describes it's preferred habitat, but data from New Jersey has shown that it has become well adapted to artificial containers such used tire casings.
  23. Ochlerotatus aurifer — Found occasionally in the spring and early summer. Vicious biting pest of humans and other mammals. Larvae are found in the spring in open marshes. — Common late spring and summer mosquito. Fierce biting pest of humans and other mammals. Larvae are abundant in late spring and found occasionally during the summer in woodland pools, swamp borders and grassy hummock areas. This long-lived mosquito is the primary suspect in the transmission of heartworm to dogs and a possible suspect in the transmission of EEE from birds to humans.
  24. Ochlerotatus cantator — A mosquito more common in salt marsh areas, but has been collected in the Central Massachusetts area. Larvae can be found in freshwater habitat that received runoff from streets and highways that receive salt during the winter. Is considered a pest of man, but not considered common in this area. when adult samples are found, it is likely that they developed elsewhere.
  25. Ochlerotatus communisOchlerotatus communis is a true snowpool species, common throughout the northern United States and Canada into Alaska. Throughout its range, the species is associated with heavily forested areas at high elevations. Ochlerotatus communis larvae are most common in deep snowpoolsfilled with dark colored water in forested areas above elevations of 1500 ft. In most cases, Oc. communis is the only large mosquito in the pools although in some years, small numbers of another northern species, Ochlerotatus provocans, may be intermixed.
  26. Ochlerotatus decticus — This species overwinters in the egg stage and is considered univoltine. The larvae occur in sphagnum lined depression in open bogs.
  27. Ochlerotatus diantaeus — Aquatic stages live in temporary or semi-permanent water bodies, in peat bogs, forest ponds and ditches, sometimes in open marshes and rock pools. Wood et al. (1979) suggest that the long antennae of the larval stages may indicate a peculiar feeding behavior. The species is monocyclic larvae appear in mid or late spring, stemmed from overwintering eggs. Adults emerge from May onwards to July and are present during the summer months. Females feed on mammals, including man, mainly at dusk and dawn. Transmissions of parasitic diseases to humans are not known at present.
  28. Ochlerotatus dorsalisOchlerotatus dorsalis has distribution that extends over the greater portion of North American northern Europe and into Asia. In the United States, the mosquito reaches greatest abundance from the plains states to the Pacific coast. In the east, it has been reported in lesser numbers across the Great Lakes states to the east coast states of Massachusetts, Connecticut and New Jersey. Ochlerotatus dorsalis overwinters in the egg stage and the eggs hatch after flooding during the first warm weather in the spring. Oc. dorsalis is well known for its capacity to migrate long distances. The adults are strong fliers and have been traced for 22 miles in Utah and more than 30 miles in California. As a result, the mosquito has been recognized as a chance migrant in some areas of its range. Ochlerotatus dorsalis larvae occur in a variety of habitats including both brackish and freshwater. They are found in large numbers on tidal marshes of the Pacific coast. The species is also common along the margins of the Great Salt Lake in Utah. Ochlerotatus dorsalis can be found in a variety of freshwater habitats including marshes, temporary pools formed by precipitation, natural springs and irrigation water. The larvae Oc.dorsalis have been found in association with numerous other mosquito species. In Utah, the species has been found breeding with 18 other species of mosquitoes including Ochlerotatus vexans, Culextarsalisand Culiseta inornata. In New York, under saline conditions, the larvae have been found with Ochlerotatus sollicitans.
  29. Ochlerotatus excrucians — Very common mid spring and early summer mosquito pest of humans and other mammals. Larvae are found in a wide range of wetland habitats. This mosquito is a suspect in the transmission of heartworm to dogs. Isolated specimens have been found throughout the summer months.
  30. Ochlerotatus fitchiiOc. fitchii is a mosquito of the northern United States and Southern portion of Canada. Its range extends from Maine to New Jersey on the eastern seaboard, west to northern Nevada and north into British Columbia. Oc. fitchii is a univoltine species with a typical northern Ochlerotatus life cycle. In Massachusetts, the single generation of eggs hatch in April and the larvae reach 4th instar during the early part of May. Egg hatch may be staggered during the early season and a variety of instars can be collected from different habitats in the same geographic area. Adults are on the wing in May, blood feed and deposit their eggs which do not hatch until the following spring. Oc. fitchii has been reported from a wide variety of habitats but the species is most common in semi-permanent bodies of water in open areas that support emergent vegetation.
  31. Ochlerotatus grossbeckiOc. grossbecki is recognized as a mosquito of the southeastern United States, but the species is found in Massachusetts on occasion. The mosquito occurs at low levels throughout the more southern areas of the state. Oc. grossbecki is one of the earliest mosquitoes to hatch from overwintering eggs. Development is rapid, considering the cold water that is present in the early Spring. Oc. grossbecki is on the wing before most mosquito control agencies put out their surveillance traps, however, the species persists until early summer and can be represented in low numbers in trap collections during May and June. The larvae of Ae. grossbecki are most common in flooded woodlands where mature Red Maple and Beech are the dominant trees. Decomposing leaves add tannins to the aquatic habitat and in most cases, habitat water is so dark that a white dipper submerged more than 2 ft below the surface cannot be clearly detected.
  32. Ochlerotatus hendersoni — Larval habitat is water-filled treeholes in the forest canopy. The overwintering stage is the egg. Host preference is for mammals, but little is known about the biology of this rarely collected species. It is a multivoltine species, with adults seen from June – August.
  33. Ochlerotatus implicatusOchlerotatus implicatus is one of the earliest species to emerge as adults in Canada, developing in temporary snow or rain pools in woodland areas. It is one of the most widely distributed species in Canada south of the tree line, but is seldom found in high enough concentrations to be considered a nuisance. Adults tend to be short lived, and while it bites vigorously in shaded conditions during the day, its low numbers make it generally not significant. Belton (2007) does not include this species on his list of potential WNV vectors.
  34. Ochlerotatus intrudens — Larval habitat is temporary and semi-permanent woodland pools, marshes, bogs, and grassy drainage ditches. The overwintering stage is the egg. Host preference is mammals and the females are persistent human biters that attack during the day and night, but the species is relatively uncommon in New England. It is a univoltine species.
  35. Ochlerotatus japonicus japonicus — New species found in Massachusetts in 2000. This species was first found in New York & New Jersey in 1998, then Connecticut in 1999. This mosquito is native to Japan, Korea, Taiwan, and southern China. It's preferred habitat is artificial containers and discarded tire casings. It is not believed at this time to be a voracious biter of man, however research done by CMMCP has shown it can be a pest. West Nile Virus has been isolated from this species. — Larval habitat is temporary woodland snowmelt pools, roadside ditches, swamps and bogs. The overwintering life stage is the egg. Its host preference is for mammalian blood to other potential hosts. Females bite humans readily during the day in shaded areas and in the evening in open areas. Virus isolations in Connecticut have found Jamestown Canyon Virus in this univoltine species.
  36. Ochlerotatus punctor — Females of this species are very similar to Ochlerotatus abserratus and can be difficult to differentiate from this other spring brood, univoltine species. Its larval habitat is in temporary woodland pools and sphagnum bogs in densely wooded mixed and coniferous forests in high elevations. Females are persistent human biters that mostly attack at dawn, dusk and early evening. They also bite during the day in wooded areas and enter houses after dark. Uncommon in New England.
  37. Ochlerotatus sollicitans — Very common summer mosquito found primarily along the coast. This aggressive mosquito will bite on a hot sunny day and is known to fly long distances, so it occasionally turns up in our district. Larvae are found on the edges of salt marshes.
  38. Ochlerotatus sticticus — The larval habitat of this species is temporary woodland pools in floodplains of rivers and large streams. The overwintering life stage is the egg. It’s a univoltine species with larvae active from May – August. Host preference is varied, from mammals and birds to reptiles. Females are aggressive human biters that may attack during daylight hours. Virus Isolations in Connecticut have shown several viruses: Cache Valley, Eastern Equine Encephalitis, Jamestown Canyon, Trivittatus and West Nile.
  39. Ochlerotatus stimulans — Spring mosquito that has been shown by data collection to be found well into the summer months. Has a singe generation like all spring mosquitoes, and is not considered a vector of disease at this time. Readily bites mammals, and can be a common pest in the spring.
  40. Ochlerotatus taeniorhynchus — The black salt marsh mosquito is a severe biter of man and livestock along the southern coasts from North Carolina to Florida and in the Caribbean. Unchecked populations can have a major economic impact. While capable of transmitting eastern equine encephalitis and St. Louis encephalitis in the laboratory, it is not a major vector of these diseases in nature. It is, however, an important natural vector of dog heartworm and Venezuelan equine encephalitis. The black salt marsh mosquito is found on the coastal plains from Massachusetts to Texas, in California along the Pacific Coast and in the Caribbean. It is more abundant in the south. This mosquito breeds in the upper regions of grass salt marshes where it is generally associated with spike grass (Distichlisspicata) and salt meadow hay (Spartinapatens). In the south, production also occurs in the high marsh associated with mangroves, saltwort (Batismaritima) and glassworts (Salicornia species). It also breeds on dredge disposal islands along the Atlantic Intracoastal Waterway. During the mosquito season, a portion of each egg clutch will hatch when flooded. Productive salt marsh sites are flooded at irregular intervals by wind or lunar tides, or heavy rainfall. Bacteria and other microorganisms provide an abundant food supply. in the field, hundreds to thousands of mature larvae often form tightly clustered "balls" which are thought to be associated with feeding, Under optimal conditions, emergence of adults can occur in as little as six days following egg hatch. Host seeking occurs in the evening and to a lesser extent in the morning. Females do not seek hosts to any great extent during darkness. In daytime, hosts that move near resting females may be attacked. The black salt marsh mosquito will feed on birds as well as mammals. All populations in Florida exhibit some autogeny which refers to an ability of females to develop eggs without taking a bloodmeal. At northern latitudes, eggs enter diapause in response to decreasing day length and water temperature breeding can occur year round in the extreme south.
  41. Ochlerotatus thibaulti — This species is an exceptionally early season mosquito species and fourth instar larvae can frequently be collected as early as the 3rd week of March. Larval instars are mixed during the early season, however, and in some years specimens can be taken from suitable habitat into the month of May. During the earliest portion of the season, Ae. thibaulti appears to be the only species present within the crypts that characteristically hold larvae. As the season advances, Cs. melanura becomes an associate species. In some areas, Ae. canadensis becomes common in the surrounding swamp habitat and occasional specimens sometimes enter the recesses where Ae. thibaulti are found.
  42. Ochlerotatus triseriatus — Common summer mosquito. A pest of humans and other mammals. Most of these larvae actually are found in old rimless tires, although some are found in other shaded artificial containers and in tree holes. When this mosquito is a pest, it's breeding source is usually close by. West Nile Virus has been isolated from this species in 2000.
  43. Ochlerotatus trivittatus— Common summer mosquito. Larvae are found in floodwater pools in both swamps and marshes. This pest is a persistent biter, and will even bite during the day.
  44. Orthopodomyia signifera — Larval habitat of this species is treeholes and artificial containers (e.g., discarded tires). The overwintering life stage is reported to be egg or larva. Host preference is avian, with adult females are rarely collected in CO2–baited CDC light traps. It is a multivoltine species. — The overwintering life stage of this species is the egg. Larval habitat is temporary grassy pools and roadside ditches in sunlit areas. Larvae are predaceous and cannibalistic. Host preference is for mammalian blood. Females are aggressive and persistent human biters that will attack anytime of the day or night. This species is not attracted to CDC CO2–light traps. No virus isolations have been reported out of Connecticut. It is a multivoltine species.
  45. Psorophora columbiaePsorophora columbiae, formerly known as Ps. confinnis, is a widespread pest from Florida, where it is known as the "glades mosquito", to New York. Scattered populations exist in Massachusetts and across the United States westward to California. The species is found in Mexico, Central America, the Caribbean and South America to Argentina. Psorophora columbiae reaches its greatest abundance in the rice growing areas of the southwestern U.S. where astronomical numbers, similar in magnitude to the production of saltmarsh mosquitoes, may occur. Eggs are deposited on moist soil which is subject to flooding by water from rainfall or irrigation. The incubation period is about 3-5 days in the rice growing areas of Arkansas. The larvae mature rapidly during the hot summer, often developing from first instar to pupae in as few as 3.5 days. The larvae develop in temporary shallow freshwater pools and puddles where there is vegetation. The larvae may occasionally be found in slightly brackish water. Ideal sites for production of larvae are ricefields, grassy roadside ditches, and grassy swales. The normal flight range of this mosquito is at least 6-8 miles however, much longer distances have been recorded. The mosquito is readily attracted to light, and the New Jersey light trap is commonly used to monitor populations. The females are furious biters in day or night. Hosts include any warm blooded animal however bovine blood seems to be preferred. — This is a multivoltine species with preferred larval habitat in temporary woodland pools and depressions in shaded floodplains. Host preference is for mammals, and females are aggressive human biters that attack anytime of the day or night when disturbed in the vicinity of their wooded larval habitats. Virus isolates report from Connecticut are Cache Valley, Eastern Equine Encephalitis, Highlands J, Jamestown Canyon, Trivittatus and West Nile.
  46. Toxorhynchites rutilus septentrionalis — Predatory mosquitoes in the genus Toxorhynchites are the most common arthropods which have been used for control of "container-breeding" mosquitoes. The combination of carnivorous larvae and innocuous adults is very attractive in biological control. Successful biological control has been reported using Toxorhynchites species from Japan, Southeast Asia, the Caribbean and the United States. Most of the 71 species of Toxorhynchites are found in forested tropical regions throughout the world. At least one, Toxorhynchitesrutilus, has a subspecies (septentrionalis) that is found as far north as 40 degrees N latitude in Connecticut and southern New York. Limited collections have been made in the CMMCP area in Millbury and Worcester. The other subspecies of Toxorhynchites rutilus found in mainland United States, Tr. rutilus, has been reported only from Florida, Georgia and Louisiana. Toxorhynchites are unusually large mosquitoes the wingspan may exceed 12 mm the body length may exceed 7 mm. Adults are frequently covered with iridescent scales and the proboscis has a pronounced 90 degree downward curve. Fourth instar larvae may be more than 2 cm in length. Adults feed on plant nectars. A few species are precocious and do not need nectar to initiate oviposition. Protein used in reproduction is apparently entirely derived from larval feeding, although some nectars may provide modest amounts of some amino acids. Cumbersome in flight, they are most frequently seen resting near treeholes or engaging in their characteristic elliptical oviposition flight patterns at the mouth of natural and man-made containers. They are not known to oviposit in small ponds or other open water such as ground pools. Larvae feed on the living macroinvertebrates inhabiting flooded treeholes, bromeliads and man-made containers. They are dependent on movement for prey location. Although they are more successful in feeding on mosquitoes, eating as many as 400 larvae during their larval development periods, they can successfully complete larval development with artificial protein sources such as water fleas (Daphnia) or brine shrimp. Cannibalism is not uncommon, especially in small containers, but containers such as tires with ample food supplies may support half a dozen or more similarly sized larvae. Larval behavior is especially intriguing with feeding dependent on prey size and availability. Wanton killing of prey without feeding has been reported. All known species are multivoltine. In the United States, Toxorhynchites generally overwinter as late larval instars. Diapause is controlled by day length, rather than temperature. Although the use of Toxorhynchites alone is unlikely to reduce pest or vector species below operational thresholds, they can be a valuable tool in areas where containers and treeholes contribute substantially to the standing crop of mosquitoes. However, they are highly susceptible to insecticides, and care has to be exercised in the timing of release of Toxorhynchites and application of insecticide sprays. Their large size and docile appearance create the opportunity for them to serve as focal points for public awareness campaigns aimed at the cleanup of man-made containers that are used as breeding sites by pest mosquitoes.
  47. Uranotaenia sapphirinaUranotaenia sapphirina is found from southeastern Canada to Florida along the eastern seaboard of the United States. Its range extends into the central states west to North Dakota and south into Mexico. Uranotaenia sapphirina has a life cycle that is similar to many of the Culex species. The adult females enter hibernation after they have been inseminated in the fall, pass the winter in a state of torpor and emerge in late spring to initiate a multivoltine breeding season. The species lays unique egg rafts that float partially submerged on the water's surface. Larvae are rarely evident until July, but peak sharply during the month of August. Larvae persist in prime breeding habitat into the month of September but decline sharply with the onset of cool weather. The brightly ornamented adults do not fly far from their breeding site but are readily attracted to artificial light. Light traps that are placed near suitable breeding habitat frequently give an overestimation of this species' population density during the summer months. Uranotaenia sapphirina is a mosquito that is almost always associated with permanent and semipermanent ponds that support rich stands of emergent and floating vegetation. In many areas of Massachusetts, Duckweed (Lemnasp.) appears to be an indicator plant. The larvae often congregate in large numbers among the tiny leaves and trailing roots of this floating aquatic plant. Water depth can vary from a few inches to several feet in the swampland utilized by this species. Uranotaenia sapphirina larvae usually avoid shade and are usually found in greatest abundance in sunlit areas of the breeding habitat.
  48. WyeomyissmithiiWyeomyiasmithii belongs to the tribe Sabethini, a group of 12 mosquito genera that share more biological than taxonomic characteristics. The tribe is well represented in the New World tropics. Wyeomyia is the only sabethinegenus that occurs in North America. Wyeomyiasmithii has a distribution that extends from Newfoundland south to Delaware, west to northern Illinois and northwest into Saskatchewan. The mosquito's distribution corresponds to the range of the northern pitcher plant, Sarraceniapurpurea gibbosa. Another pitcher plant mosquito, Wyeomyiahaynei, is found in the southern pitcher plant, Sarraceniapurpurea venosa, from Maryland to South Carolina. The range of the two pitcher plant mosquitoes does not appear to overlap. Wyeomyiasmithii is a multivoltine mosquito that completes its entire life cycle in the immediate vicinity of its predacious host plant. The females deposit their eggs directly on the water within the plant or just above the waterline in older leaves. The larvae live in the liquid of the plant and feed on the carcasses of insects and spiders being digested by the plant enzymes. Multiple generations take place from spring through fall. Late in the season, the females attach eggs to young leaves, before they become filled with water. The species overwinters as a larva frozen in a block of ice within the plant. The overwintering larvae pupate during the month of May and are usually on the wing by June. Wyeomyiasmithii is an obligate inhabitant of the predacious pitcher plant and has never been reported from any other larval habitat.

Credit must be given for the information complied here to Dave Henley at the East Middlesex Mosquito Control Project, Dr. Wayne Crans at Rutgers University (retired), Tim Deschamps and Curtis Best at the Central Massachusetts Mosquito Control Project, as well as the Massachusetts Entomologist group.

Watch the video: ESCAPE TO THE COUNTRY 2022 Suffolk S22E5 Mon Oct 11, 2021 (December 2021).