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iiigrolineatus and alhijncUis, the latter D. hunteri, pm'umnpertus, 

 xcnuatus, occidcntdlls aud raritihilis. Tlie present pai)ev deals 

 witli the distribution, hosts, life-history and liahits, and the 

 economic importance of JJ. (dbipictvs, hunteri and nIfjTolineatus. 



J), liunteri, Bishopp, has been only found in Arizona, near 

 Quartzsite and Supai (200 to 3,000 ft. alt.) on the mountain 

 sheep {Ovis canadensis gaillardi), the parasites becoming- en- 

 gorged and dropping- off the hosts during the fall and winter. 

 None of the immature stages of the species have been taken in 

 nature, but it is probable that tliey engorge on small wild 

 mammals. In the laboratory the larvae, nymphs and adults were 

 fed on guinea-pigs. The predominance of males, especially 

 durinj? the summer months, indicates that they remain on the 

 mountain sheep for some time after the females drop off. This 

 tick has not been collected on domestic animals, and the infested 

 mountain sheep examined were apparently healthy and the one 

 which bore the g-reatest number of ticks (ca. 35) was in fine 

 condition. 



In the United States, D. alhipictus, Packard, has been found 

 in Texas, New Mexico, Arizona, California, Idaho, Montana, 

 Utah, "Wyoming, Oregon and Washington. Little is known 

 reg-arding the distribution of the species in Canada, although it 

 undoubtedly occurs in the southern part of the Dominion. Dr. 

 C. Gordon Hewitt states that this tick was taken at Huntingdon, 

 B.C. from a horse which had been imported from Oregon ; also 

 in Quebec from elk (wapiti) brought from Wyoming. Since this 

 species does not drop from the host to moult, the hosts from 

 which adults have been taken must be considered as harbouring 

 the immature stages as well. The host of the typical form is 

 the moose, but the elk or wapiti is also commonly attacked, and 

 the tick has also been found on the beaver. The horse is pre- 

 ferred as a host among domestic animals, but the ox is frequently 

 infested. A sing-le female of D. alhipictvs was collected from a 

 mule deer (Odocoileus hemionns) killed near Darby, Montana. 

 Many adults and some nymphs were also found on mountain goat 

 in the same locality. The tick has been reared experimentally 

 from larva to adult on the guinea-pig and tame rabbit, as well 

 as on the ox and horse. On a number of occasions larvae of this 

 species w^ere placed on sheep and goats, but a few that were 

 attached died two days later, and hundreds died in the greasy 

 wool without being able to reach the skin. In the warmer 

 portion of the country (e.g., Texas) where this tick occurs the 

 larvae may hatch during- the summer but remain inactive until 

 cool weather. In the colder parts of its range (e.g., Montana) the 

 hatching* does not take place until late summer or fall. In either 

 case the larvae attach themselves to hosts when favourable 

 weather prevails during- autumn, winter and spring. 



Until very recently D. alhipictus has been considered of little 

 or no economic importance. But the authors' investigations show 

 that it is an important pest of horses, and, in a lesser degree, of 

 cattle. In California, Oregon and Montana horses and colts 

 become very weak, and the latter not infrequently succumb if 

 the ticks are not promptly killed. During' the spring-, in terri- 

 tory infested by the Eocky Mountain spotted fever tick 



