THE FLIES THAT CAUSE MYIASIS IX MAX 105 



The Family HYPODERMATIDAE 



This family is here considered in the more restricted sense, as used in 

 Townsend's "Manual of Myiology," and is approximately equivalent to 

 the Hypodermatinae of Pleske (113) and Seguy (135). Many au- 

 thors have considered it a part of the Oestridae or Larvaevoridae 

 (Tachinidae). 



With the exception of some of the rarer species which are not known 

 to be of medical importance, the flies are rather robust and beelike in 

 appearance and more or less densely clothed with bushy hair. The 

 front is wide, especially in the females; the third antennal segment 

 is short and rather strongly receding into the second; the epistoma is 

 widened and shieldlike; the head and thorax, in all species of known 

 medical importance, lack well-developed bristles ; the hypopleura, how- 

 ever, possess tufts of strong hairs; the lower squamae are strongly 

 developed and much larger than the upper ones; cell r 5 is strongly 

 narrowed at the apex, and the anal vein is short, though sometimes 

 prolonged by a fold; the middle and hind femora, at least, are thick- 

 ened at the base. 



The adult flies take no food and are rarely seen except in the vicinity 

 of their hosts. The normal hosts of the different species include 

 various mammals, particularly cattle, deer, reindeer, antelopes, and 

 rodents. Man occasionally is an abnormal host of three species that 

 have been recorded, all in the genus Hypoderma. 



The Genus HYPODERMA Latreille 



Synonyms. — Atelecephala Town send ; Litliohypoderma Townsend. 



This genus may readily be distinguished from the other members of 

 this family known to science by the following combination of charac- 

 ters: The clypeus is hollowed out to receive the antennae, but the 

 two antennal foveae are separated by a narrow carina, the width of 

 which is less than the diameter of the third antennal segment ; this 

 carina, however, does not extend below the antennal pockets (fig. 52). 

 The clypeus is pilose; palpi are completely absent. The bristles of 

 the head, thorax, and abdomen are undeveloped. The tibiae are di- 

 lated in a dorsoventral axis in the middle. The seutellnm is bare and 

 polished at the apex, and more or less distinctly notched in the middle. 



Life Histories. — Eggs are attached to hairs on the lower part of 

 the body, usually the legs, of the host. They hatch without friction or 

 moisture, and the young larvae immediately burrow into the skin at 

 the base of the hair. The supposition that eggs are taken into the 

 digestive tract and hatched there has been disproved. The first -stage 

 larva makes its way by a more or less circuitous route through the 

 intermuscular connective tissues, finally lodging in the back of the 

 animal. In the course of its wanderings it may penetrate the spinal 

 canal. The larva then forms a pocket, or warble, in the connective 

 tissue of the back, cuts a hole through the skin to the surface, and 

 molts, in the process of which it loses its functional mouth hooks. 

 The third larval stage is also passed within the warble, the mature 

 larva then making its way out and dropping to the ground to pupate. 

 The completion of the life cycle takes a year, most of which is spent 

 in the bodv of the host. 



