ON ENTOMOLOGY. 43 



F/v herself was only about one-third of an inch ; and he computed that 

 there were about20, 000 young in the coil. When this extraordinary fecun- 

 dity is considered, we need not wonder at the countless swarms which 

 appear, as if by magic, upon a joint of meat during hot weather. Like 

 most female insects, the Mother Fly dies in a few days after giving birth 

 to her numerous brood ; but, unlike Oviparous Flies, she seems to take a 

 considerable time to deposit the whole. It would be impossible, indeed, 

 for her pouch to contain the larvae if they were all hatched at the same 

 time ; and therefore it has been so ordered by Providence that they 

 should arrive at maturity in succession. 



From the early death of the mother, Reaumur conjectured that they 

 did not scruple to eat their way through her bowels ; but he disproved 

 his supposition by a most decisive experiment. He too'c a Fly, which 

 had already deposited a few larvae, and closed the natural opening of the 

 pouch with sealing-wax, so that it was impossible any more could make 

 their exit there. The mother lived several days longer than she would 

 have done had she been left at liberty to produce her young, but not one 

 of them attempted to force a passage, after having been shut up for ten 

 days. 



The COMMON GNAT (Culex Pipiens) constructs a boat-shaped raft, 

 which will float, of eggs heavy enough to sink in the water, if dropped 

 into it one by one. The eggs are nearly of the pyramidal form of a gun- 

 powder flask, rather pointed at the upper, and broad at the under end, 

 with a projection like the mouth of a bottle. 



The first operation of the Mother Gnat is to fix herself by the four fore 

 legs to the side of a bucket, or upon a floating leaf, with her body level 

 with and resting upon the surface of the water, excepting the last ring 

 of the tail, which is a little raised ; she then crosses her two hind legs in 

 form of an X, the inner opening of which is intended to form the scaf- 

 folding of her structure. She accordingly brings the inner angle of her 

 crossed legs close to the raised part of her body, and places in it an egg 

 covered, as is usual among insects, with a glutinous fluid. On each side 

 of this egg she places another, all which adhere firmly together by means 

 of their giue, and form a triangular figure, which is the stern of the raft. 

 She proceeds in the same manner to add egg after egg in a vertical posi- 

 tion, carefully regulating the shape by her crossed legs ; and as her raft 

 increases in magnitude, she pushes the whole gradually to a greater dis- 

 tance, and when she has about half-finished she uncrosses her legs, and 

 places them parallel ; the angle being no longer necessary for shaping 

 the boat. Each raft consists of from two hundred and fifty to three hun- 

 dred and fifty eggs, which, when all laid, float on the water secure from 

 sinking, and are finally abandoned by the mother. They are hatched in 

 a few days, the Grubs issuing from the lower end ; but the boat, now 

 composed of empty shells, continues to float till it is destroyed by the 

 weather, 



Kirby justly describes this little vessel as resembling a London 



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