ENTOMOLOGY

41!e SANITARY ENTOMOLOGYan important role in producing FISTULOUS WITHERS. He considersDermacentor albipictus Packard as the worst offender, but alsoconsiders D. andersoni Stiles (venustus Banks) as a cause. D. albipictusis commonly called a winter" tick and in some regions of British Columbiawhere poll evil and fistulous withers are common, horses are heavilyinfested with these ticks. The favorite ,site of attachment is along thewhole length -of the mane from the pon to the withers. At the point ofattachment there is oiten a necrotic spot if the tick has been attached fora few days. It is easy to see that these necrotic spots should be afavorite point of entrance for bacteria.It is quite probable that most of the cases of abscesses and irritationresulting from tick bites are due to secondary infections by bacteriawhich may possibly be mechanically introduced by the tick itself. Noone has given this question serious attention.DISEASES OF UNKNOWN ORICINThere are quite a number of instances of so-calledJick fever caused bythe bite of ticks, of which the exact cause is unknown. Among these areunnamed TICK FEVERS caused by Ornithodoros savignyi Audouin(Koch) and Hyalomma aegyptium (Linnaeus) I{och.•HEART WATER, a disease of sheep, caused by a filterable virus, istransmitted by Amblyomma hebraeu;m Koch.The TICK FEVER OF MIANA is caused by the bite of Argaspe18ic'U8 Oken.INTERMITTENT FEVER of Wyoming, which is possibly identicalwith Rocky Mountain Spotted Fever, is thought by Castellani and Chalmersto be caused by Dermacentor andersoni Stiles (venust'U8 Banks).ROCKY MOUNTAIN SPOTTED FEVER, a disease characteristicof the Rocky Mountains of Montana and Idaho and occasionally othernearby states, was proven by Ricketts to be transmitted by the tickDermacentor anilersoni Stiles (venustus Banks), by D. variabilis (Say)Banks and possibly by D. modestus Banks.The first scientific article in which the tick is mentioned as a possiblecarrier of this disease was published by Wilson and Chowning in 190!e.They subsequently published the reports of thcir investigations but theydid not prove that the tick was actually the transmitting agent. Anderson(1908) was so convinced that the tick was the cause of the feverthat he publishe.d an article calling it the SPOTTED FEVER or TICKFEVER of the Rocky Mountains. Stiles in 1905 did not attribute thedisease to ticks. Finally Ricketts in 1906 began a thorough investiga-