INSECTS 



491 



but is much less unlike the tsetse fly. It lays its eggs in 

 rotting matter, by preference in stable manure, for which 

 reason heaps of such substances should never be allowed 

 to accumulate near houses. The larvae hatch in one 

 day, feed on their surroundings, and pupate in a week. 

 They are soft, white, and legless, with twelve segments, 

 tapering forwards, and a head that can be withdrawn 



S.cS.ew. 



Fig. 198. — The life-history of the House Fly (Musca domestica). — 

 From Theobald. 



a, Mandible of larva with adjacent structures ; b, larva ; c, anterior spiracle of 

 the same ; d, eggs ; e, pupa case ; f, remnants of spiracle on the same. 



under the first segment and carries a pair of sharp 

 hook-like mandibles and two minute antennae. The 

 second and last segments bear each a pair of spiracles, and 

 the fifth and following segments have each a spiny pad 

 below. The pupa case is formed from the last larval skin. 

 The imago emerges a fortnight after laying, becomes 

 sexually mature in a week, and lays its first batch of eggs 

 four days after mating. It may deposit half a dozen 



