842 MOSQUITOES OF NORTH AMERICA 



Legs rather slender, moderately long ; vestiture black with a blue reflection ; 

 femora ochraceous towards base; front and middle knees narrowly silvery-white 

 scaled; scales of tibiae somewhat outstanding; fore tarsi with first joint basally 

 three-fourths white, second joint basally white; mid tarsi with first joint 

 entirely white except extreme apex, second joint basally three-fourths white, 

 third joint with some white scales at base ; hind tarsi with a sprinkling of pale 

 scales on basal half of first joint, second joint with basal half white, third joint 

 with a short white mark at base. Claw formula, 1.1-1.1-1.1. 



Length : Body about 6 mm. ; wing 5.5 mm. 



Larva, Stage IV (plate 121, fig. 418) . Head rounded, about as wide as long, 

 slightly narrowed before eyes, a notch at insertion of antenna, front margin 

 obtusely pointed. Antennas moderate, slender, smooth, with a single hair at 

 middle ; three spines at tip and a digit on a long pedestal. Eyes moderate. Both 

 pairs of dorsal head-hairs single ; ante-anteunal tufts three-haired. Mental plate 

 broad and shortly triangular, with a prominent central tooth and ten on each 

 side, of which the first eight are small and regular, the last two very large and 

 produced. Mandible subquadrangular, spined without at base; two filaments 

 from a notch before tip; an outer row of cilia from a collar; a row of slender 

 filaments from angular projections on outer margin; dentition of four teeth, 

 the first largest; a long spine before, a broad filament and five serrate hairs 

 within; process below shortly bilobed, a broad rounded prominence on outer 

 side and a short one within on basal lobe, a straight row of hairs ending in a 

 tuft ; basal angle very slight ; a scattering row of five large hairs within ; a row 

 of long hairs at base. Maxilla subcylindrical, rounded at tip, twice as long as 

 wide, divided by a band-shaped suture; inner half with a row of long coarse 

 hairs near the suture ; a cap of large, coarse, round-tipped spines covering apical 

 end of maxilla, directed slightly inwards; a single filament from middle of 

 outer half next the suture and a long spine near tip ; palpus small and rather 

 slender, with four approximated digits at apex. Lateral hairs of abdomen in 

 threes on third to fifth segments. Air-tube conically tapered, about three times 

 as long as wide; pecten of very dense, coarse short teeth running to middle of 

 tube, followed by a single long hair ; single pecten-tooth a broad stout spine with 

 two or three stout basal branches. Lateral comb of eighth segment an irregular 

 patch of few scales; single scale elliptical, evenly fringed with stout spinules, 

 of which the terminal three are longer. Anal segment a little longer than wide, 

 with a dorsal plate reaching over halfway down the sides ; dorsal tuft a long hair 

 and brush on each side; a single lateral hair; ventral brush well developed, 

 preceded by some small tufts along ventral line; anal gills short and broad, 

 lanceolate, showing a very slight central trachea. 



The larvae live in the water in hollow trees. Mr. Knab got them twice in such 

 situations, once in the forest, far from habitations and unassociated with other 

 species, and once in town and associated with other tree-hole inhabiting mos- 

 quito larvae. 



Semi-arid region of southern Mexico. 



Tehuantepec, State of Oaxaca, July 1, 1905 (F. Knab) ; Salina Cruz, State 

 of Oaxaca, July 15, 1905. 



Aedes knabi varies in the thoracic ornamentation of the imago. In some of 

 our specimens the two longitudinal lines are hardly perceptible, while in others 

 the lines are very distinct, owing to the predominance of the black hair-like 

 scales. Some specimens also show indistinct darker areas basally above roots 

 of wings. 



