. Smithsonian miscellaneous collections. enknown to kill horses and cattle through induced nervousness and theloss of blood. It is serious also as a pest of humans, particularlywhere abundant in the neighborhood of summer resorts. Both thehorn fly and the stable fly are potential carriers of such livestock dis-eases as anthrax and surra. The horn fly has been claimed, fromexperiments on monkeys, to be a vector of human poliomyelitis, butmore recent tests (Herms, 1939) appear to give negative any case, these flies well illustrate how an ordinarily harmlessorgan such as the insect lab
. Smithsonian miscellaneous collections. enknown to kill horses and cattle through induced nervousness and theloss of blood. It is serious also as a pest of humans, particularlywhere abundant in the neighborhood of summer resorts. Both thehorn fly and the stable fly are potential carriers of such livestock dis-eases as anthrax and surra. The horn fly has been claimed, fromexperiments on monkeys, to be a vector of human poliomyelitis, butmore recent tests (Herms, 1939) appear to give negative any case, these flies well illustrate how an ordinarily harmlessorgan such as the insect labium, by a few anatomical alterations canbe converted into an instrument of torture. 44 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 104 XII. LOUSE FLIES. FAMILY HIPPOBOSCIDAE The Hippoboscidae are a family of winged or wingless bloodsuckingflies parasitic on mammals and birds. They cause their hosts muchphysical annoyance, but because they do not ordinarily leave an ani-mal until the latter dies, they have little relation to the spread of. Fig. 16.—Louse flies, Lynchia and Melophagns. Hippoboscidae. A, Lynchia americana (Leach), a parasite of hawks and owls (length of headand body about 8 mm.). B, Melophagus ovinus L., the sheep tick (largestabout 8 mm. long). C, same, vestigial wing and associated bristles. D,Lynchia americana, right hind tarsus and claws. E, same, single foot claw. F,Melophagus ovinus, right fore tarsus and claws. disease, though certain species have been shown to be vectors ofpigeon and quail malaria. Most of the species are permanently winged(fig. 16 A), some shed the wings after having established themselveson a host, and a few are practically wingless (B), the wings in suchspecies being reduced to minute lobes (C). In all species the clawsof the feet are conspicuously large and recurved (D, F). Those of NO. I BITING AND DISEASE-CARRYING FLIES SNODGRASS 45 the winged species shown in the figure are two-branched, each clawhaving a large basal lobe (E) separ
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