83 



than an accessory control measure, its indirect value through cleaning 

 and clearing the land being probably greater than its value in the 

 destruction of ticks. 



Every effort is being made to increase the knowledgs of the residents, 

 whose ignorance on these matters is often surprising, and it is intended 

 to publish and distribute among them a brief bulletin on tick control. 



It is not at present considered necessary to attempt the extermina- 

 tion of mammalian hosts of the tick other than the Columbian ground 

 squirrel [Citellus cohmibianus], though in the future such a course 

 may be found necessary in certain cases, such as the mountain goats 

 from the vicinity of the tick districts. 



Parker (R. E.). Second Report on Investigations of the Rocky 

 Mountain Spotted Fever Ticlc in Eastern Montana. — 3rd Bienn. 



Rept. Montana State Bd. Entom., 1917-1918; Helena, ISth 

 December 1918, pp. 41-54. [Received 7th March 1919.] 



The investigations into the habits and host -relationships of the 

 Rocky Mountain spotted fever tick [Dermacentor venustus] which 

 were begun in 1916 [see this Review, Ser. B, v, p. 80] were continued 

 in 1917 in eastern Montana. The character of the country was found 

 to have a fundamental influence on the abundance of the tick, the 

 hilly, rocky country of this part of the State serving as an admirable 

 habitation for the small host-animals of the larval and nymphal 

 ticks. A table shows the results of examination of wild mammals 

 for larvae and nymphs of the tick. Of these, the jack rabbit is the 

 most important, being a host of all stages of the tick and being suscep- 

 tible to the disease ; next in importance is the deer mouse. A correla- 

 tion is noticeable between the abundance of ticks and that of rabbits 

 preceding or accompanying occurrences of the fever, e.g., the unusual 

 prevalence of the disease in northern California in 1915 and 1916 was 

 preceded by great rabbit abundance in 1914 and 1915. In eastern 

 Montana the disease in 1915, 1916 and 1917 moved steadily 

 westward while the height of rabbit abundance preceded or 

 seemed to be coincident with it. It is believed that cottontail rabbits 

 are more important tick hosts than the results of examination show. 

 Examination of wild mammals for adult ticks showed 100 per cent, 

 of infestation for porcupines, 71 per cent, for jack rabbits and 11 per 

 cent, for cottontail rabbits. Among domestic animals, the horse is 

 the most efficient host of adult ticks. While in one locality very 

 few ticks were found on cattle, in another they proved to be 

 important hosts. Pigs may sometimes carry a considerable number of 

 ticks ; observations on sheep have not been made to any extent, but 

 evidence indicates that they may suffer heavy infestation. 



In most regions of eastern Montana, ticks are unusually abundant 

 only during occasional seasons or possibly in some places during two 

 successive seasons, with an interval of several years between the 

 periods of abundance. In the area recently examined adult ticks 

 appeared early in April and were abundant during May and the 

 first half of June, after which they declined rapidly, though considerable 

 numbers were found even in August. Larval ticks were first collected 

 on 21st May and nymphs on 5th April. Both were still abundant 

 on 25th August. Seed ticks and nymphs were both numerous in 

 June,, the former being most abundant later in the season. 



