95 



Mosquito control in any area within reach of a salt marsh depends 

 on the prevention of breeding on that marsh. Drainage has not 

 eliminated all the breeding, but has brought it within control. The 

 writer believes that frequent and regular night collections of mos- 

 quitos on the wing should be made throughout the breeding season. 

 The cost of control in the three counties is given ; the cost on the 

 upland increases per unit area as the population grows denser, but the 

 per capita cost decreases as the density of population increases. The 

 results of control appear in increased comfort and health and in increase 

 in property values. A census taken by the writer has shown that the 

 large majority of the population of the counties is in favour of the 

 continuance of the work. 



Cooley(R. A.). The Spotted Fever Tick {Dennacentor venustus, Banks) 

 and its Control in the Bitter Root Valley, Montana. — J I. Econ. 

 Eniom., Concord, viii, no. 1, February 1915, pp. 47-54. 



The paper presents a summary of our knowledge of the spotted fever 

 tick, Dermacentor venustus, and outlines the control work now in 

 progress. This tick is the carrier of Rocky Mountain spotted fever, 

 and is responsible for " tick paralysis " in man and certain domestic 

 animals. It has been recorded in Washington, Oregon, Idaho, Mon- 

 tana, Wyoming, Utah, Colorada, California, and extends northward 

 into British Columbia. The larvae and nymphs occur on practically 

 all the small mammals in the valley, especially the ground squirrel 

 {Citelhis columbianus), the pine squirrel {Sciunis hudsonicus richardsoni) 

 and the chipmunk {Eutanias luteiventris). The adults feed chiefly 

 on horses and cows. Consequently, ticks practically disappear when 

 the limit of the range of domestic animals is reached. Beyond this, 

 in the natural habitat of the Rocky Mountain Goat, the tick is 

 exceedingly abundant. Outside the goat ranges, the numbers are 

 insignificant, except in the mountains near Victor. These facts have 

 an important bearing on eradication ; domestic animals can be con- 

 trolled by dipping or other means. If the species is prevented from 

 laying eggs, the tick must disappear, and the disease with it. The 

 life-cycle continues over two years at least ; if the adult fails to secure 

 a host during the first season which follows nymphal feeding, it can 

 pass into the ground in July and reappear next year, thus making the 

 cycle three years. The following methods of control may be used : — 

 (1) The destruction of the ticks before egg-laying by the use of arsenical 

 dip ; this method has been found very effective and, in future, will 

 probably have a wider application ; (2) the destruction of rodents, 

 especially the ground squirrels, as they are largely responsible for 

 maintaining a food supply for the ticks. Since, however, the early 

 stages feed on other animals, other means will eventually be needed. 

 Grazing sheep over tick-infested country may be useful, since many 

 adults are killed in the wool. 



The work of control is conducted by the Montana State Board of 

 Entomology, the United States Bureau of Entomology and the United 

 States Public Health Service. The State Board was created in 1913 

 and has authority to enforce regulations for the eradication of the 

 spotted fever tick ; the two federal services are engaged in work in 

 Bitter Root valley, and are subject to the State Board. There is no 



