820 MOSQUITOES OP NORTH AMERICA 



blackish-brown, nude. Pleuras brown, coxae luteous, clothed with patches of 

 elliptical silvery-white scales and rows of dark bristles. 



Abdomen subcylindrical, flattened anteriorly, tapering and compressed pos- 

 teriorly, the venter with a median ridge and with the fifth, sixth and seventh 

 segments apically expanded; dorsal vestiture bluish-black, a row of lateral, 

 basal, quadrangular, segmental silvery- white patches; venter black-scaled, 

 banded with white at bases of segments. Cerci black. 



Wings moderate, hyaline; petiole of second marginal cell shorter than its 

 cell, that of second posterior cell also slightly shorter than its cell ; basal cross- 

 vein distant more than its own length from anterior cross-vein; scales dull 

 brown, costa with a bluish reflection, a short narrow line of white scales at its 

 base, outstanding scales of veins narrowly ligulate, dense and slightly broader 

 on second vein. Halteres whitish. 



Legs slender, rather long; vestiture violet-black; fore femora black-scaled 

 throughout ; mid femora beneath broadly silvery white on basal three-fourths, 

 tips rather broadly ringed with white ; hind femora with a black ring at base 

 and before tip; fore tarsi with a minute white spot at base of first joint; mid 

 tarsi with first joint black, ringed with white at base and apex, second joint 

 white on basal third; hind tarsi with base and apical fourth of first joint and 

 basal third of second joint white-ringed. Claw formula, 1.1-1.1-0.0. 



Length : Body about 3.5 mm. ; wing 3.5 mm. 



Male. — ProbOTcis straight, rather slender, black scaled. Palpi slightly 

 shorter than the proboscis, slender ; apex of long joint and two last joints slightly 

 thickened and rather sparsely clothed with long black hairs; vestiture black, 

 somewhat roughened. Antennae plumose, the last two joints long and slender, 

 rugose, pilose, black, the others short, sordid luteous, ringed with black at in- 

 sertions of hair-whorls; hairs of whorls long, dense, dark brown. Coloration 

 similar to female. Occiput silver-scaled, with two small, dark subdorsal spots 

 anteriorly. Mesonotum silver-scaled on anterior three-fifths, the hind margin 

 of silvery area transverse, uninterrupted. Abdomen elongate, subcylindrical, 

 the fifth, sixth and seventh segments apically expanded beneath; eighth seg- 

 ment dorsally silver-scaled, with black apical margin; lateral dilation mod- 

 erate, coarse, pale yellowish. Wings narrower than in the female, the stems 

 of the fork-cells longer, the vestiture less abundant. Claw formula, 3.1-2.1-0.0. 



Length : Body about 4.5 mm. ; wing 3.5 mm. 



Genitalia (plate 33, fig. 317) : Side-pieces over twice as long as wide, 

 rounded at tips, apical lobe absent, basal lobe undeveloped. Clasp-filament 

 small, slender, with an articulated terminal spine half as long as filament. 

 Harpes elliptical, concave, the inner margin revolute, tip pointed and recurved. 

 Harpagones with a short columnar base bearing a &ie seta near the tip and a 

 terminal articulated long narrowly ligulate filament. Unci approximate, 

 revolute, forming a large basal cylinder. Basal appendages very short, bearing 

 three rather long spines. 



Larva, Stage IV (plate 118, fig. 405).— Head rounded, widest through eyes; 

 antennse rather long, slender, uniform, smooth, a single hair near middle; 

 both pairs of dorsal head-hairs single. Body with the skin smooth. Lateral 

 comb of eighth abdominal segment of many scales in a patch, each scale with 

 the margin evenly fringed, without differentiated central spme. Air-tube 

 moderately stout, about three times as long as wide, tapering outwardly; pecten 

 of fourteen teeth, reaching nearly to the middle, followed by a single small tuft 

 of six hairs at a considerable interval. Anal segment longer than wide, with a 

 dorsal plate reaching well down the sides; dorsal tuft a long hair and tuft on 

 each side; lateral tuft small, five-haired; ventral brush well developed, with 

 ( smaller tufts before the barred area; anal gills about as long as the segment, 

 stout, tapering, equal. 



