208 THE HOUSE-FLY 



still less do I refer to that horrible insect, Lucilia homini- 

 vorax, which used to cause the death of so many French 

 convicts in Cayenne by laying its eggs in the mouths and 

 nostrils of its sleeping victims. My concern is only with 

 that irrepressible little imp whose gyrations may be 

 observed in almost any inhabited apartment in the realm. 

 This creature is bred of corruption; without corruption 

 it cannot exist, for its eggs, numerous as they are, require 

 the heat generated by putrescence to vivify them, and 

 the toothless maggots hatched from the eggs are so 

 equipped as to derive nourishment only from substances 

 disintegrated by decay. 



Choosing, therefore, a suitable nidus, either in ordure 

 or rotting vegetable matter, the parent Musca deposits 

 the comparatively insignificant number of four or five 

 score eggs, neatly arranged with her ovipositor, from 

 which in about four-and-twenty hours are hatched the 

 legless maggots. These larvae eat voraciously, and grow 

 with great rapidity; one of them has been observed to 

 increase one-third of its own length within twenty-four 

 hours. On the fifth or seventh day, the outer skin 

 hardens and turns brown, as the larva changes into the 

 pupa or chrysalis stage. The next five or seven days are 

 passed without movement ; but a wonderful operation is 

 in progress within that tight little case, altering the 

 inmate from a simple worm-like creature to a highly- 

 organised dipterous insect. The metamorphosis com- 

 plete, the dry skin cracks, and out crawls a pale, flabby 

 ghost of a house-fly, with pulpy, clammy wings, incapable 

 of flight, and a curious membrane on the forepart of the 

 head, which rises and falls with the action of the tracheae 

 or breathing apparatus. A brief exposure to the atmo- 



