MOTIONS OF INSECTS. 367 



being observable in several others of the family, par- 

 ticularly ■ in a still smaller fly with black pellucid 

 wings (Molobrus ?), and not uncommon in summer, 

 whose extremely rapid motion we have often admired 

 as it performs its minute gyrations on a leaf or the 

 petal of a flower. 



It was no less remarkable, that the two snowy- 

 winged gnats just mentioned were male and female, 

 as the latter is seldom seen, and when the males 

 swarm upon a window, a single female can scarcely 

 be found ; but though they were flirting about on the 

 same page, they took not the slightest notice of one 

 another, and each went through its gyrations as if 

 unconscious of the other's presence. The female, 

 besides, contrary to what is usual among insects, was 

 by far the most alert and agile of the two; inso- 

 mucli that, though it was early in March, we at first 

 mistook her for the minute summer fly alluded to in 

 the last paragraph.* 



From all we have observed, we think it probable, 

 that notwithstanding the apparent sociality of the 

 dancing gnats (^Vi'puHdcp)^ they do not congregate in 

 consequence of any gregarious feelings, or for mutual 

 assistance ; but merely because they are produced 

 in numbers in the same places, and individually 

 prefer similar haunts. The individual sportive move- 

 ments of the two snowy-winged flies just described, 

 which were performed on the contiguous pages of a 

 book, or severally at the top and bottom of the same 

 page, prove that they do not consider the presence 

 of numbers indispensable. This position is farther 

 illustrated by the proceedings of an insect of a very 

 difierent family — the whirlwig beetles ( Gyrinidce, 

 Leach), which may be seen on the surface of every 

 pool weaving their eccentric dances, and twinkling 

 their polished corselets in the sun, both in summer, 

 and, as we have remarked, throughout the winter. 

 * J. R. 



