. Animal parasites and human disease. Medical parasitology; Insects as carriers of disease. CONTROL OF TABANIDS 489 only by men who spend the day in the forest, and is most prevalent in May and June, a time corresponding to the appearance of many tabanids, points strongly to these insects as the carriers of the infection, since they are the only diurnal insects exclusively found in forest regions. The forest leishmaniasis of Paraguay may also be due to tabanids. In one other case a tabanid is implicated in the spread of a disease. In the tropical jungles of Africa certain species of Chrysops l
. Animal parasites and human disease. Medical parasitology; Insects as carriers of disease. CONTROL OF TABANIDS 489 only by men who spend the day in the forest, and is most prevalent in May and June, a time corresponding to the appearance of many tabanids, points strongly to these insects as the carriers of the infection, since they are the only diurnal insects exclusively found in forest regions. The forest leishmaniasis of Paraguay may also be due to tabanids. In one other case a tabanid is implicated in the spread of a disease. In the tropical jungles of Africa certain species of Chrysops locally known as mangrove flies, serve as in- termediate hosts for filarial worms. Leiper and other investigators have found that the larvae of the loa worm, Loa loa, which swarm in the peripheral blood of the host in the daytime only, undergo rapid development in Sev- Fig. 227. A deerfly, Chrysops callidus. eral Chrysops, especially x 4' C. dimidiata and C. silacea, and probably also C. centurionis (see p. 309). It is probable that other species of Chrysops, including our own deerflies (Fig. 227), would be able to serve as intermediate hosts for the worms, in which case there is danger that this form of filarial disease, if introduced into America or other countries, might become endemic. Control. — Prevention of bites from tabanids, especially dur- ing an epidemic of anthrax, or in places where diseases believed to be transmitted by tabanids are prevalent, is an important mat- ter. Practically the only means that can be employed is the use of repellents, as for other insect pests (see p. 455). Accord- ing to Herms, repellents efficient against tabanids usually con- tain fish oil. In a recent publication Portchinsky, a Russian entomologist, having found that tabanids have the peculiar habit of skimming over pools, touching the lower side of their bodies to the surface, advised the conversion of such pools into traps by pouring oil on them to produce a surface film, so that th
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