654 MOSQUITOES OF NORTH AMERICA 



Coquillett described Culex nivitarsk from two specimens and none have been 

 since collected. Dr. C. S. Ludlow suggested to us that these specimens were only 

 aberrations of A. canadensis, and we have adopted this view. We have 

 examined the types (one male and one female in the collection of Dr. John B. 

 Smith) and find the markings of the legs dissimilar on the two sides. The larvae 

 of the two forms are indistinguishable. The following is a detailed description 

 of nivitarsis, drawn up from the type specimens. 



Female. Proboscis rather long, cylindrical, uniform, tip scarcely widened, 

 labellffi conically tapered ; vestiture black ; setae very small, curved. Palpi short, 

 stout, about one-fifth the length of the proboscis; vestiture of bluish-black 

 scales, the apices white-scaled and with rather short black setse. Antennae with 

 joints subequal, black, rugose, pilose, the second joint a little longer and pale 

 at extreme base; tori subspherical, Avith a cup-shaped apical excavation, deep 

 yellowish, with a patch of small black setas on inner side ; hairs of whorls sparse, 

 moderate, black. Clypeus shortly conical, prominent, nude, blackish. Occiput 

 brown, densely clothed with narrow curved scales on vertex, flat ones on sides ; 

 scales pale yellow dorsally, white on the sides, some blackish ones intermixed 

 subdorsally ; margin of eyes silvery-white scaled ; many erect, forked, pale scales 

 on the nape ; setae along margins of eyes coarse, black. 



Prothoracic lobes elliptical, remote dorsally, clothed with scales colored like 

 those on vertex of head, and with numerous pale bristles. Mesonotum brown, 

 vestiture of small, narrow, curved scales, golden brown dorsally, pale golden 

 along anterior and lateral margins and around antescutellar space ; bristles mod- 

 erate, black, numerous above roots of wings. Scutellum trilobate, gray, clothed 

 with pale-golden scales, each lobe with a group of brownish bristles. Postnotum 

 elliptical, prominent, brownish luteous, nude. Pleurae and coxae luteous, clothed 

 with flat white scales and short pale bristles. 



Abdomen subcylindrical, flattened, posteriorly tapering; dorsal vestiture of 

 black scales with a slight greenish or coppery reflection, a narrow band of dull- 

 white scales widening laterally at base of each segment; first segment with a 

 patch of black scales in the middle, a few white ones on each side, and with many 

 fine pale hairs ; venter entirely whitish scaled except for triangular black patches 

 on posterior lateral margins of posterior segments; the white of venter and 

 lateral spots has a silvery sheen; cerci black; setae fine, moderately abundant. 



Wings rather broad, hyaline, faintly smoky ; petiole of second marginal cell 

 about two-thirds as long as its cell, that of second posterior cell shorter than its 

 cell ; posterior cross-vein distant about its own length from anterior cross-vein ; 

 vestiture of veins entirely black, outstanding scales on apical portion of wing 

 dense, narrowly ligulate. Halteres whitish, with a slightly darker knob. 



Legs rather slender ; femora largely pale beneath, above a few black scales 

 with silvery sheen; tibiae largely white, clothed with black scales along outer 

 edge ; tarsi all covered with a silvery sheen that renders the markings obscure, 

 irregularly marked, as follows: right and left fore tarsi practically alike, the 

 first and second joints black with white rings at base and apex of each, third 

 joint narrowly white at base, the last two joints black with a slight whitish sheen 

 at incisures ; on right mid tarsus the first joint is all white, the second with a 

 black ring towards base, the third narrowly white at base, the fourth and fifth 

 black ; the left mid tarsus has the first joint with a black ring at middle, the 

 second and third black with white rings at base and apex, the fourth and fifth 

 joints white ; hind right tarsus white, the second, third, and fourth joints with 

 black median rings, the ring of second joint faint ; the left hind tarsus is broken, 

 only the first joint remaining. Claw formula, 1.1-1.1-1.1. 

 Length : Body about 5 mm. ; wing 4.5 mm. 



