Ochlerotatus canadensis (Theobald, 1901), original combination: Culex canadensis.
Subfamily Culicinae, genus Ochlerotatus. Subgenus Culicada currently includes a single species with two recognised subspecies. Subgenus abbreviation – Cda.
The species and subspecies of subgenus Culicada are characterised and distinguished from the other species and subgenera of Ochlerotatus by the following combinations of characters. Characters that diagnose Culicada in the phylogenetic analyses of Reinert et al. (2009) are indicated by an asterisk (*).
ADULTS – *Eyes contiguous immediately above antennal pedicels; antennal pedicel with few dark scales on inner surface; maxillary palpus of females entirely dark-scaled, palpomeres 3–5 of males with basal pale bands; proboscis dark-scaled; scutum with uniform covering of yellowish scales, *scutal fossal scales sparse; *scales all dark on anterior part of antealar area; *pronotal scales all narrow; hypostigmal area, anterodorsal area of mesokatepisternum and lower third of mesepimeron bare, *upper prealar scales absent; lower mesepimeral setae absent; postprocoxal membrane bare; *hindfemur without pale scales at apex; tibiae dark-scaled with ring of pale scales at base and apex; wing entirely dark-scaled; first tarsomere of fore- and midlegs with conspicuous basal pale band, other fore and midtarsomeres mostly dark-scaled (second tarsomere usually with basal and apical pale spot, third tarsomere usually with at least basal pale spot), hindtarsomeres 1–4 with conspicuous basal and apical pale bands (*hindtarsomere 1 and *hindtarsomere 2 with apical pale scales), hindtarsomere 5 entirely pale-scaled; *midungues of males both toothed, larger one with 2 teeth; abdominal terga of females mainly dark-scaled with basolateral pale patches, sometimes with complete transverse basal pale bands (*tergum III without median basal pale scalepatch), terga of males with inversely U- or V-shaped basal pale bands connected to triangular lateral pale patches. FEMALE GENITALIA – *Posterior margin of tergum VIII convex; *sternum VIII with seta 2-S inserted more or less directly lateral to seta 1-S, MALE GENITALIA – Gonocoxite with prominent basal dorsomesal lobe bearing dorsally oriented setae, apical dorsomesal lobe with short stout setae; *gonostylus/gonocoxite index ≥ 0.73; *claspette filament stout, spiniform, circular in cross section. LARVAE – Seta 4-C inserted more or less directly mesad of seta 6-C; setae 5-C and 6-C usually with 5 branches; *seta 7-C 0.41–0.81 length of dorsal apotome; setae 2-P and 3-P < 0.5 length of seta 1-P; seta 5-P single; seta 8-P longer than seta 10-P; seta 1-M minute; *seta 6-II as long or longer than seta 6-III; *seta 3-VII 0.48–0.85 length of segment X; comb scales in patch; pecten spines evenly spaced; *seta 1-S 1.15–1.99 width of siphon at point of insertion; saddle incomplete; seta 1-X usually single, inserted at margin of saddle; seta 2-X multi-branched, fan-like, ventral brush (seta 4-X) with precratal setae. PUPAE – *Seta 5-CT more than 1.3 length of seta 4-CT; s*eta 3-II as thick or thicker than seta 1-II; *seta 5-II longer than seta 3-II. See genus Ochlerotatus.
There is no evidence or speculation about the evolutionary affinities of Oc. canadensis prior to the studies of Reinert et al. (2008, 2009). In the morphology-based phylogeny of Reinert et al. (2009), this species, the sole member of subgenus Culicada, was recovered in a sister relationship to a large clade comprised of eight subgenera and 22 unclassified species of genus Ochlerotatus.
The immature stages of Oc. canadensis are found primarily in temporary and semi-permanent ground pools in woodlands, but are also found in ditches, pools in stream beds, cattail and sedge marshes, muskeg pools and bogs. Habitats are usually shaded by trees and shrubs but larvae can be found in pools in open areas such as prairie. Adult females feed mainly on mammals but will also feed on amphibians, birds and reptiles. They readily attack and bite humans in shaded places during daylight hours in western areas of North America but seldom annoy and feed on humans in eastern areas.
North America, from the Yukon Territory eastward to Newfoundland of Canada and southward throughout the United States into Mexico.