FLY LARVAE 175 



from five to ten hours longer, and that these larvae 

 when hatched were smaller than those hatched out in 

 the open. The eggs are oval and cylindrical, one 

 twenty-fifth to one-twentieth of an inch long and 

 about one-hundredth of an inch wide, and of a dull, 

 chalky-white colour. 



The little larva has not been seen emerging from 

 the egg-case, but probably, as in the case of the meat- 

 or blow-fly, Musca vomitoria, the eggshell splits longi- 

 tudinally and the maggot pushes its way out. The 

 length of the newly-hatched larva in its first stage (or 

 instar) is seven-hundredths of an inch, and it remains 

 in this stage about twenty-four hours, when it casts 

 its skin and appears as a larger maggot three- 

 twentieths of an inch long. In this condition it 

 remains from twenty-four to thirty-six hours. After 

 a second moult the maggot attains the length of one- 

 quarter of an inch, and in this stage it remains five or 

 six days. During its life the larva moves actively 

 about amongst its surroundings, eating up the decay- 

 ing matter, but avoiding bits of straw and hay. There 

 is some evidence to believe that, if pressed for food, 

 larvae may devour one another. After living altogether 

 some five to seven days, the larva somewhat suddenly 

 turns into a dark brown pupa or chrysalis. The 

 transition takes place very rapidly in the course of 

 a few minutes and the pupa remains enclosed in the 

 last larval skin. After another period of five to seven 

 days in normal circumstances the insect hatches out, 

 at first running around with soft and baggy wings, 

 which, however, soon stretch out, harden, and dry. 

 It is worthy of note that whereas Howard found the 

 complete metamorphosis to take ten days, and Packard 

 from ten to fourteen days, in the cooler climate of 

 Manchester Hewitt finds it takes from twenty to 

 thirty days. The last named gives some interesting 

 particulars as to the effect of the weather upon the 



