The Hump-Backed Plies 



hump-backed fly. In the District of Columbia and in New 

 Hampshire the fly may be found in midsummer darting about 

 the moving ants on tree trunks and elsewhere and finally suc- 

 ceeding in laying its egg, sometimes after a struggle, on the 

 neck of the ant. The egg hatches and the young larva bores 

 directly into the head of the ant. As it enlarges it eats out the 

 whole head cavity, the head breaks off from the body of the ant 

 and moves about independently, propelled by the body of the 

 contained maggot which extrudes partly from the neck hole. 

 The larva of the fly transforms to pupa within the last larval skin 

 in the cut off ant's head and the adult fly issues in the course of 

 from two to three weeks. To see an ant's head walking off by 

 itself is a curious sight, yet it is common enough where this fly 

 abounds. Dr. Fox named it, appropriately enough, "the ant- 

 decapitating fly." 



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