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Hump-backed Flies

(Family Phoridae.)

The little dark flies of this family have no popular name, unless we adopt that of Comstock, "the hump-backed flies," which is characteristic enough. They may easily be recognized by the two very dark, thick veins on the front margin of the wings. There are not many species, but individuals are excessively common in this country, flying in swarms, and frequently being found upon window panes. Their larval habits are various, but they breed in decaying animal and vegetable matter. The flies lay their eggs on dead chrysalids, on dead snails and in decaying vegetation, and the maggots which hatch develop rapidly. They are slender, and the pupa which is contained in the hardened last larval skin breathes by means of two slender processes issuing from the fourth segment. There has been some discussion as to whether the larvae of the flies of this family are ever directly parasitic in other insects, but it seems to be accepted that one species is a true parasite in the hives of the honey bee and a most interesting form has recently been discovered which is a true parasite of ants. In other cases, these flies undoubtedly lay their eggs on diseased or dying insects.

Life History of the Ant-Decapitating Fly

(Apocephalus pergandei Coquillett.)

It would be rather a misnomer to call this a typical life history since this form seems peculiar in its habits and rather aberrant among the Phoridae, but the observations which have been made upon it by Dr. W. H. Fox and Mr. Theo. Pergande have been more complete than any which have been made upon other members of the family, so it is here included. A common black ant, Camponotus pennsylvanicus, is the host of this little 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 succeeding 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 antdecapitating fly."