878 CHARLES PAUL ALEXANDER 



as discussed elsewhere in this paper (page 705). Kiedel (1909:29) 

 describes in some detail the habits and swarming of H. bicolor (Meig.), 

 the males of which are very active in the forenoon during the hours of 

 brightest sunlight, the females resting on the willow branches near by. 

 Similar habits are recorded by Riedel (1910:30) for H. saxonum (Lw.). 

 The immature stages of the European species are practically unknown, 

 the only original reference being that of Von Roser (1834), who states that 

 the larvae of H. nigra Latr. live in the sand along the banks of streams. 



Hexatoma megacera (0. S.) 



1859 Anisomera mejzcera 0. S. Proc. Acad. Nat. Sci. Phila., p. 242. 



The adult flies of Hexatoma megacera are on the wing during the months 

 of May and June and may be swept from the rank vegetation along the 

 streams from which their larvae emerged. The following notes on copu- 

 lation, resting positions, egg laying in nature and in captivity, and other 

 details, are quoted from published field observations (Alexander, 1915 c: 

 143-145) : 



May 14, 1911 This usually rare insect was common on a grassy plot of land along 

 Cascadilla Creek [Ithaca, New York]. The flies sit on the blades of grass, the long antennae 

 of the male directed straight ahead. The males are very poor fliers and prefer to drop to the 

 ground when disturbed and clumsily work their way off along the ground. When approached 

 from the side they are much more easily alarmed and fly away. When approached from 

 above, they do not move until the stick, finger, or whatnot, is within a couple of inches, 

 when they remove the fore feet from the support and, on nearer approach, fall to the ground. 

 When in copulation, the female tries to disengage by rapidly vibrating the wings in attempted 

 flight, repeating this often, from every one to five seconds until disengaged or exhausted. 

 The male can disconnect himself at will. In copulation the female is always uppermost 

 unless exhausted, when both sexes lie flat on a grass-blade. The female has the head up, 

 the male the head downward; copulation always takes place on a vertical support, usually 

 a blade of grass, sometimes a plant stem. The sexes remain in copulation for quite a long 

 time and are perfectly motionless. All of the legs of both sexes are on the support unless 

 in a position where this is physically impossible, in which case as many as possible are used; 

 the hind legs of both sexes are held at right angles to the support, the forelegs in front. After 

 copulation the female generally drops to the ground, the male, after a few moments' rest, flies 

 away. Specimens in copulation were found in abundance from 2 to 4.30 p.m. when no more 

 could be discovered. From 4.30 to 7 p.m. solitary males were common, but no females could 

 be found on the grass-blades. At 4.30 p.m., a few females were found clinging to the trunks 

 of the willow trees about two feet from the ground. At 5.30 p.m., females were noted in 

 small groups over the water, evidently engaged in oviposition, as they frequently dipped 

 down to the surface. These latter were in company with a large swarm of dancing empidid 

 flies (Rhamphomyia). Of the great numbers that were picked from grasses in the after- 

 noon a considerable proportion were females and toward 5 p.m. they commenced egg-laying 

 on the sides of the containing vessel, large shell vials. By 7 p.m. the sides of the vials were 

 black in places with the large, dark-colored eggs. This data would seem to place the time 

 for oviposition at about sunset. The females are very good fliers and often travel for long 



