50 



JOURNAL OF ECONOMIC ENTOMOLOGY 



[Vol. 8 



nus mountanus) a region which is very wild and very inaccessible, this 

 tick is exceedingly abundant. There appears to be an exception to the 

 limitation of ticks to the range of domestic animals, in the mountains 

 near Victor, where, as Doctor L. D. Fricks has pointed out, ticks con- 

 tinue to be abundant beyond these Hmits. Outside of this exception, 

 the number of adult ticks that engorge on wild animals either in the 

 valley floor, the first reaches in the mountains, or deeper into the 

 mountains below the goat ranges, is so small as to be of no particular 

 significance from a control standpoint. Or, in other words, if those 

 which develop on domestic animals were entirely eliminated, ticks 

 would scarcely ever be seen by those who reside in the valley and in- 

 fections would cease. 



The ticks are more abundant than elsewhere along the border coun- 

 try, between the valley and the mountains. The presence of a known 

 danger there makes this border country less desirable for tillage pur- 

 poses and it is naturally given over to pasturage, and, as ground squir- 

 rels are abundant there, the conditions are made perfect for a continua- 

 tion of the difficulty. 



The host relationships may be summarized then by saying that 

 the mature stages are fed on small mammals only and the adults, prac- 

 tically speaking, are confined to domestic animals, so far as the habit- 

 able valley is concerned, with the exception of a certain mountainous 

 district back of Victor. 



These facts have an important bearing on eradication. Domestic 

 animals can be controlled. By dipping and by other means they may 

 be kept free of ticks and if the species is prevented from engorging and 

 laying eggs, it must die out, and with the disappearance of the tick, 

 the disease must go. 



However, certain facts connected with the seasonal history also 

 have an important bearing on control and these are now discussed. 



Seasonal History 



Previous workers had believed that the tick completes the life cycle 

 in one year. When in 1911 detailed records were secured this was 

 found to be quite impossible. It was found that the winter is passed 

 both as adults and as nymphs, but that the hibernating individuals 

 of these two stages belong to different generations. On these grounds, 

 therefore, it was necessary to conclude that the life-cycle is at least 

 two years long. 



In connection with longevity studies, it has been shown that adults 

 which fail to secure a host during the first season following nymphal 

 feeding, do not die but go down to the ground during July and 

 come up again the next year, in the spring, and continue to wait for a 



