72 THE LIFE-STORY OF INSECTS [CH. 



alone used for flight, though the hind-wings modified 

 into tiny drumstick-like 'halters' are the organs of a 

 fine equilibrating sense is perhaps the most special- 

 ised, structurally the 'highest' of all insects. Yet in 

 a week or two this swift, alert, winged creature is 

 developed from the degraded maggot, white, legless, 

 headless, that buries itself in putrid flesh, 'feeding 

 on corruption.' 



The broad end of the maggot is the tail, while the 

 narrow extremity marks the position of the mouth. 

 Above this are a pair of very short feelers (fig. 21 c), 

 while from the aperture project the tips of the mouth- 

 hooks (fig. 21 e,f), formidable, black, claw-like struc- 

 tures, articulated to the strong pharyngeal sclerites 

 and moved by powerful muscles, tearing up the fibres 

 of the flesh. On either side of the prothorax is an 

 anterior spiracle, a curious branching or fan-like out- 

 growth (fig. 21&), with a variable number of tiny open- 

 ings which are probably of little use for the admission 

 of air to the tubes. In many maggots the mouth- 

 hooks and the front spiracles become more and 

 more complex in form in the successive instars. The 

 cuticle, white and smooth to the unaided eye, is seen 

 on microscopic study to be set with rows of tiny 

 spines which assist the maggot's movements through 

 its food-mass. At the tail-end the large hind spi- 

 racles are conspicuous on a flattened dorsal area of 

 the ninth abdominal segment ; each shows a hard 



