The Mosquitoes of Canada 87 



Abdomen generally without the median stripe, idahoensis Theobald 



13. Mesonotum typically with central broad undivided dark band. ... 14 

 Mesonotum with central dark band, if present, distinctly divided . . 15 



14. Mesonotum creamy yellow at the sides hirsuteron Theobald 



Mesonotum gojden or reddish brown at the sides ; median stripe some- 

 times divided, or mesonotum uniformly dark brown, punctor Kirby 



Mesonotum contrastingly yellow at the sides. . .aurifer Coquillett 



15. Mesonotum with paired brown lines 16 



Mesonotum uniformly dark brown, without lines 17 



16. Mesonotum yellowish, lines narrow, well separated ; a very small 



species aldrichi Dyar & Knab 



Mesonotum yellow (or gray), sometimes more or less suffused with 

 brown centrally, the margin remaining yellow; lines narrow, some- 

 times obsolete; miedium sized species, .lazarensis Felt & Young 



Mesonotum yellow (rarely gray), the dark lines broad, heavy, well 

 con'trasted a.nd passir^ back around the ante,-scutellar space; a 

 larger species pionips Dyar 



Mesonotuta yfollow, lines slender, often conjointed into a median 

 stripe ; legs very deep black diantaeiis Howard, Dyar & Knab 



Mesonjotum yellow, the side stripes darker and heavier than the 

 median pair; small species, cor^fined to Pacijfic coast region, 



cyclocercidus Dyar 



Mesonotum yellow; lines moderate, normal; medium sized species, 

 confined to Pacific Coast region leuconotips Dyar 



Mesonotum yellow to brown; lines distinct, broad; a large species, 

 confined to Pacific coast region aboriginis Dyar 



Mesonotum gray, with central brown shade, lines fine, dark; a small 

 species impiger Walker 



Mesonotum mossy yellow; lines narrow and very approximate, 



pullatus Coquillett 



17. Thorax with long hairs, especially below nearcticus Dyar 



Thorax with normal setae 18 



18. Mesonotum light gray, with traces of dark lines, or a central brown 



shade, sometim^es covering the whole mesonotum; a small species, 



prodotes Dyar 

 Mesonotum dark gray, often with whitish shades at each side; a 



large species trichurus Dyar, 



Mesonotum uniformly dark brown; a medium sized species, very 



fond of entering houses intrudens Dyar 



As indicated above, the variation in colour of the mesonotum is con- 

 siderable in the same species, so that the characters overlap on all sides. 

 The male genitalia are of great assistance to determination in such cases, 



