AEDES ATROPALPUS 641 



filaments near tip and an outer row of cilia; fourteen closely set filaments on 

 outer edge; dentition of four teeth on a process, three spine-shaped ones before, 

 three blunt ones at base, a broad serrate filament and eight hairs within ; process 

 below narrowly cleft in the bulbous tip, with patches of hair and a row of 

 stouter hairs ; five filamentous hairs within and four at base. Maxilla elongate 

 hemispherical, contracted before tip, divided by a band-shaped suture ; inner 

 half hairy, a crown of hairs at tip ; outer half with a patch of hair, two filaments 

 near suture and a spine on the other side ; palpus three times as long as wide, 

 with four digits and two irregularities at tip, one of the digits short. Thorax 

 rounded, slightly wider than long; hairs abundant, subdorsal prothoracic ones 

 very short. Abdomen moderate, the posterior segments more elongated ; hairs 

 rather short, lateral tufts multiple to fifth segment, double on sixth. Tracheal 

 tubes broad, band-shaped, slightly expanded in the segments, narrowed pos- 

 teriorly but with distinct segmental expansions in the seventh and eighth seg- 

 ments. Air-tube short and stout, tapered beyond base, hardly twice as long as 

 wide; pecten reaching nearly to tip, the distal four or five teeth larger and 

 detached; single tooth a long spine, broad at base, with one to four basal 

 branches ; a multiple hair-tuft a little beyond middle of tube, well within the 

 pecten. Lateral comb of eighth segment of many scales in a triangular patch ; 

 single scale elliptical, base pointed, fringed all around, the five terminal teeth 

 of about equal length. Anal segment as long as broad, dorsal plate reaching 

 halfway down sides ; dorsal tuft a brush and hair on either side ; a single lateral 

 hair; ventral brush well developed, but sparse, without small tufts preceding- 

 barred area. Anal gills large, very long, rather broad, with conspicuous trachese. 



Pupa (plate 150, fig. 712). Thoracic mass narrowly pyriform, slightly 

 depressed at base of antennae and behind head; thorax rugose on dorsal line; 

 air-tubes moderate, expanded, the tips slightly notched. Abdomen stout, rather 

 long, the basal segments strongly angled ; hairs slight, subdorsal ones long on 

 central segments, a small tuft on hind angles of eighth segment; anal paddles 

 with a long terminal seta. 



The larvae live in pot-holes in rocks along streams, which are filled at high 

 water or by rains, and in crevices in rocks along the shores of lakes, that are 

 filled by waves in storms. The eggs are deposited singly on the sides of the 

 hole, above the water-level. There are apparently several generations in a year, 

 these depending on the raising of the water-level in the rock-pools which causes 

 the eggs to hatch. Females confined in a glass jar laid their eggs singly on the 

 water during the summer, but in patches adhering to the sides of the jar in the 

 fall. The winter is passed in the egg state, the eggs being evidently firmly 

 attached to the rocks. The larvae develop rather slowly. They feed mostly on 

 green algae. Both larvae and pupae are unusually heavy, being little if at all 

 lighter than the water. The larvae therefore stay near the bottom with the 

 greatest ease, and are doubtless enabled to stay down for long periods owing 

 to the well-developed anal gills. Even the pupse will rest motionless below the 

 surface, and are not obliged to get under some object in order to remain below 

 as most Aedes pupae do. Breeding is confined to the rock pools, and the adults 

 are seldom taken far from the breeding-places. The females are active biters, 

 and very annoying along some of our rocky streams. Owing to its very local 

 occurrence and the restricted number of possible breeding-places, the species 

 is never extremely abundant, and only troublesome locally under special 

 conditions. 



North-eastern United States. 



Center Harbor, New Hampshire, September 17, 1902 (H. G. Dyar) ; White 

 Mountains, New Hampshire (H. K. Morrison) ; Cummington, Massachusetts, 

 July 5, 1903 (F. Knab) ; Westfield, Massachusetts, July 14, 1903 (F. Knab) ; 



