WEALTH OF INSECT LIFE 



197 



FIG. 172. Robber-fly (Erax cinerascens) 

 one and one-half times natural size. 



specialized forms, such 

 as the house-fly, when 

 they are ready to escape 

 there forms upon the 

 front of the head a sort 

 of balloon, which blows 

 off, as it were, the end of 

 the pupal case, and al- 

 lows the fly to walk out. 

 Then the bladder - like 

 forehead gradually re- 

 cedes and the head be- 

 comes normal. 



Fleas.- -These aberrant insects are by some authori- 

 ties placed in a separate order ; by others in a suborder 

 of the Diptera. They are wingless insects, with body 

 compressed, legs well developed, and adapted for jump- 

 ing. The female lays about a dozen eggs. These are 



deposited in the dust accumu- 

 lated in cracks and crevices. 

 The larvae have a head and jaws, 

 and feed upon decaying bits of 

 animal and vegetable matter 

 found in the crevices where they 

 live. Their pupal stage is 

 passed within a cocoon spun by 



the lar/a. The mouth-parts of the adult are fitted for 

 piercing and sucking. Among domestic animals they 

 are to be found upon the cat, dog, rabbit, poultry, and 

 pigeons. There is a species which lives upon the cat 

 and dog --a flea which at times also proves annoying 



FIG. 173. A flea (Ceratopsyl- 

 lus serraticeps). Enlarged ten 



times. 



