ENTOMOLOGY

188 SANITARY ENTOMOLOGYof cattle, in some cases causing the death of many calves, especially whenthe cutaneous tumors become infested with larvre of Chrysomya.The life history and habit~ of the species have not been fully elucidated,although a number of important contributions have been made.It is generally concluded that the infestation of man is brought about inthe following indirect but very interesting manner: The eggs of the :flyare deposited on the bodies of certain bloodsucking insects, especially themosquito known as Paorophora lutzi Theobald (J anthinoaoma) , orattached to leaves frequented by these insects whence they adhereto them. The eggs are att~ched vertically on the under side of theabdomen or the legs. The embryos appear to remain dormant thoughfully developed within the egg and when the bloodsucking dipteronfinds a host, the heat of the animal or the blood taken up stimulates thelarvre to break from the shell and penetrate the skin of the host. Dermaltumors are formed by the larvre, a well-marked hole opening to the outsideas in the case of the ox warble. When the grubs become full grown theyleave the host, drop to the ground and transform to adults. The periodin the host ranges from two to six months. During this time there ismore or less inflammation and sometimes acute pain. This form is widelydistributed through tropical America. Lieut. L. H. Dunn has recordedcases of apparent transmission of the eggs by ticks.In South America Dr. J. C. Nielson has reported the occurrence of theAnthomyid flies (Mydaea anomala and M. torquena) as producing subcutaneoustumors in various birds in parts of Argentina, and Dr. C. H. T.Townsend records M. apermophilae as parasitic on nestlings in Jamaica.EURoPE.-Several cases of dermal myiasis have been reported, especiallyfrom Russia. These are attributed to infestations of larvle ofHypoderma and Gastrophilus.The infestation of reindeer in Lapland and farther south in Norwayby larvre of the Oestrid fly, Oedemagena tarandi Linnaeus, should bementioned. The infestations are almost analogous to those in cattlecaused by Hypoderma. The eggs are laid on the hair during the springand later the larvre appear in the submucous tissues of the back. Asmany as 300 have been reported as occurring in a single animal. Thissame species no doubt infests the reindeer in Alaska and Canada.AFRICA.-In Africa the outstanding form of dermal myiasis is producedby the Muscid fly, Cordylobia anthropophaga Griinberg, commonlyspoken of as the Tumbu fly (figs. 38, 39). The larvre are kuown as "Vcrdu Cay or." These develop in the skin of man and various other hostsincluding dogs (probably the preferred host), cats, horses, and otherdomestic and wild animals. The attack is painful but not serious, thoughno doubt when numerous specimens are present unpleasant symptoms follow.The life history of this form has not been entirely elucidated, but