ENTOMOLOGY

RELATION OF INSECTS TO THE PARASITIC WORMS 57Prophylaxis in the case of this tapeworm is obviously largelydependent upon fly control measures.Other TapewormsAccording to Villot (1888) the larval tapeworm observed by Stein(185~) in the larva of Tenebrio molitor belongs· to the tapeworm of themouse, known as Hymenolepis microstoma. The same writer (1878,1888) also associates with certain tapeworms of shrews, two species oflarval tapeworms which he found in myriapods, Glomeris limbata. Furtherinvestigations of these parasites appear necessary to substantiatethe views held by Villot as to their specific identity. Ackert (1918, 1919)has recently recorded some experiments in which chickens were givenhouse flies and became infested with tapeworms (Davaimea cesticillU8 andD. tetragona). The immature stages of these parasites were not, however,seen in the flies and the possibility is not excluded that the chickensbecame infected from some source other than ·the flies, notwithstandingthe precautions taken against extraneous infection. Guberlet (1919)caught stable flies (Stomoxys calcitrans) in poultry yards where thechickens were commonly infested with HymMolepis carioca (Magalhaes,1898) and fed them to young chicks with the result that some of thembf'came infested with this tapeworm. He concludes that the stable flypossibly serves as an intermediate host of this tapeworm.TREMATODA OR FLUKESAll species of flukes whose life history is known depend upon molluscsas hosts for certain larval stages, and they mayor may not require oneor more additional intermediate hosts before they reach the definitive host.n is as intermediate hosts following the first intermediate host, a mollusc,that insects can playa part in the propagation of flukes. As yet it hasnot been shown that insects are concerned in the life history of any ofthe flukes (about 100 known species) that affect human beings or domesticanimals, but as the .life history of all of these parasites has riot beendt'termined it is quite likely that in the case of SOJIle species insects will befound ~~ act as intermediate hosts.' Different species and groups ofspt'cies show various types of life history with reference to the numberof larval stages through whicJI the parasite passes and the number Qfintermediate hosts required. A comparatively simple life cycle is asfollows: The mature fluke in the definitive host produces .eggs which passto the exterior in the feces. Under suitable conditions of moisture andtemperature the egg hatches and a ciliated larva, the miracidiunn, issues.If this miracidiunn finds a suitable mollusc (different species of mollus'