ENTOMOLOGY

496 SANITARY ENTOMOLOGYspecies of importance. The species are most abundant in Africa whereseveral of them are connected with the transmission of disease. R. appendiculatuaNeumann is the principal transmitting agent of East CoastFever, a malignant disease' of cattle in Africa, and four other relatedspecies play some part in the dissemination of this malady. R. everts?'Neumann is credited with the transmission of Nuttallia equi, or biliaryfever of equines, in South Africa. R. bursa Canestrini and Fanzago transmitsBabesia ovis of sheep in southern Europe and R. sanguineu8(Latreille) Koch, a species which is present in extreme southern Texasand Florida and generally distributed throughout the tropical parts ofthe world, plays some part "in the transmission of babesiasis or malignantjaundice of dogs. The biologies of the ticks in this group are quite similarto that outlined for Ixodes and need not be repeated. With mostspecies the molts are passed off the host. R. bursa, the sheep tick, andR. everts;', the horse tick, of South Africa, are exceptions, the larvalmolt being passed on the host and the nymphal molt on the ground. Forthe. most part, the ticks of this group are general feeders.The Genus .A. mblyomma.-This group reaches its maximum developmentin South America. In the United States we have three species ofsome economic importance. The Lone Star tick, .A.. americanum Linnaeus,is the commonest of these. It is widely distributed through the countryand extends into South America. The females are readily recognized bythe single white spot on the scutum, from which the common name isderived. All of our species are general feeders and attack man freelybut are not known to carry disease. In tropical America, A. cajennenseFabricius is tremendously abundant and is often the cause of much annoyanceto man, the larvae and nymphs attaching to the skin by the hundredsand frequently ulcerated sores develop from scratching. The best knownspecies of this group all drop from the host to molt. Engorgement ofthe different stages is comparatively rapid, ranging from three days tothree weeks. The Bont tick, A. hebraeum Koch, a South African species,is capable of carrying the disease known as heart water of sheep. Lounsbury'sstudies indicate that the organism of this disease does not passthrough the egg but is taken up by the larvre or nymphs and subsequentlytransmitted by the following stage.The Genus Dermacentor.-This group reaches its highest developmentin North America. About half of the species drop from the hostto molt while the others pass the molts on animals. The most importantspecies economically is. the Rocky Mountain spotted fever tick, D. venustusBanks (or D. wndersoni Stiles of many authorities 2). This species drops• The editor has chosen to adopt anderBoni as the name for the Rocky Mountainspotted fever tick on the grounds of priority and absolute identification. (See footnoteon this species in Chapter XXIX, p. 409.-W~ .. p:~ie~ce.