. Bulletin of the Department of Agriculture. Agriculture; Agriculture. Fig. 17.—Hypoderma lineatum: Pos- terior stigmal plates of fifth-stage larva. Greatly enlarged (Laake) The fly of H. bovis (fig. 20) is considerablj^ larger and much stouter than that of H. lineatiim. This is especially true of the thorax, which is much broader. The color is similar to that of //. lineatum, but the band of yellowish hairs across the prothorax dorsally is markedly wider and the shade slightly deeper than in H. lineatum. The shiny longitudinal lines of the thorax are obscured anteriorly by the hair. The


. Bulletin of the Department of Agriculture. Agriculture; Agriculture. Fig. 17.—Hypoderma lineatum: Pos- terior stigmal plates of fifth-stage larva. Greatly enlarged (Laake) The fly of H. bovis (fig. 20) is considerablj^ larger and much stouter than that of H. lineatiim. This is especially true of the thorax, which is much broader. The color is similar to that of //. lineatum, but the band of yellowish hairs across the prothorax dorsally is markedly wider and the shade slightly deeper than in H. lineatum. The shiny longitudinal lines of the thorax are obscured anteriorly by the hair. The color of the abdominal vestiture is similar to that of H. lineatum except on the terminal segments, which have a wider and more sharply defined band of lemon yellow, distinctly paler than in H. lineatum. The wing veins of H. iovis are of a reddish-brown color. The femora and the tibige are black and well covered with black and yellow hairs, and the tarsi are brown and much less hairy than in H. lineatum. HOW THE LARV.« OF HYPODERIVU LINEATUM GAIN ENTRvVNCE TO THE HOST The method of ingress of various animal parasites is often a point of considerable economic importance. As ha^ been indicated in the historical sketch, the opinions held by various investigators in regard to the way in which Hypoderma larvae enter the host have been at wide variance • and even up to the present time there are but few who feel certain of the method of ingress of these parasites. During 1916 plans were laid at the Dallas laboratory to carrry out a series of tests to determine accurately the way in which the larvae enter the host. These tests have been continued along similar lines up to date. Since a full knowledge of the habits of oviposition of adult H. lineatum has been gained, it is evident that there are really only two waj^s in which the larvse might get into the host, one of these being by direct penetration through the skin and the other by being taken in by mouth in the Qgg or young la


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