204 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 6 



reservoir for Rocky Mountain spotted fever has been much discussed 

 by most of the investigators who have been carrjdng on work in the 

 Bitter Root Vallej'. The recent discovery, reported by Rucker,^ of 

 an infected tick on the mountain goat is of much interest. As is 

 commonly known, the disease occurs mainly on the western side 

 of the Bitter Root Valley. On this side the mountains ascend abruptl}^ 

 from the floor of the valley and thus furnish a suitable habitat for the 

 mountain goat. The goats do not come into the Valley proper but 

 during the winter frequent the more precipitous portions of the moun- 

 tains immediately adjoining the Valley at a number of points along the 

 western side. With the possibility that the mountain goat is a natural 

 reservoir for the disease virus, infected ticks in the immature stages 

 may be carried by small wild animals from the higher altitudes to the 

 lower regions where native cattle graze. The habit of the goats of 

 retreating into higher elevations as the season advances would minimize 

 this danger, however. 



A very few angora goats are kept by residents on the west side of 

 the Valley. Although we have found that this animal may act as a 

 host for adults of the spotted-fever tick, there is not sufficient evidence 

 at hand to warrant any statement regarding the possibility of this 

 animal being susceptible to spotted fever. 



Hibernation 



Inve.stigations in the Northwest during 1910 and 1911 indicated 

 that hibernation takes place only in the nymphal and adult stages. 

 During the winter of 1911, however, this idea was proven to be falla- 

 cious. Out of a total of about forty-five lots of seed ticks which hatched 

 from eggs during the summer and fall of 1911, a considerable number 

 in thirty-two lots was found to be alive and active in the spring of 

 1912, thus proving that it is possible for large numbers of the tick to 

 hibernate in the larval stage. 



A number of nymphs which were engorged by one of the authors 

 (King) during the summer of 1910 did not transform to adults until 

 the following summer, thus showing that it is also possible for the tick 

 to pass the winter in the engorged nymphal stage. Under natural 

 conditions it appears that the majority of the nymphs which drop 

 from hosts before August 15 molt to adults and hibernate in that stage. 

 The examination of a large number of hosts of the immature stages 

 in several localities shows that very few nymphs are to be found on 

 them after August 15, thus indicating that few ticks enter the winter 

 in the engorged nymphal stage. 



iRtrcKER, W. C. — Rocky Mountain spotted fever. Public Health Reports, Vol. 

 XXVII, No. 36, 1912, p. 14. 



