6 



COMMON MAMMALS OK W KSTKIiN MONTANA. 



fever is contracted through the digestive system. Of course the 

 drinking of had water may, and undoubtedly often does, cause sick- 

 ness. But thai neither water nor anything else when taken into the 

 stomach can possihly cause spotted fever is proved hy the fact that 

 even infected blood has been fed to guinea pigs, which are very 

 susceptible to this disease, without bad results. In short, spotted 

 fever, like malaria, is believed to be contracted only by blood infec- 

 tion, and not, like typhoid, through the digestive system. 



In the brief life history of the tick there are four distinct stages — 

 egg. ••-red" oi' larva, nymph, and adult. Although the adult ticks 

 have been found on mountain goats, coyotes, badgers, woodchucks, 

 snow-shoe rabbits, and on the only bear examined, by far the greater 

 number, at least 95 per cent, feed on domestic stock. When full of 

 blood the females drop from their hosts to the ground, become inac- 

 tive, and after a time lay as many as 4.000 eggs. They then die. After 

 several weeks these eggs hatch, the young ticks, called seeds, being 

 about the size of mites. These seeds then crawl up blades of grass 

 or other low vegetation and, if opportunity offers, become attached to 

 some passing small animal. After feeding on this animal for from 

 three to eight days they become full of blood, drop off, and seek 

 shelter. Then, after remaining inactive for a few days, they molt 

 ami emerge as nymphs, which somewhat resemble wood ticks, but 

 are very much smaller. These nymphs, like the seeds, attach to 

 some small animal — never, so far as known, to men — feed for a few 

 days, drop off, become inactive, molt, and after about two weeks 

 emerge as the third and last stage, the familiar wood tick. Thus 

 the life cycle is completed in from one to three years. 1 Any tick 

 failing to find a host in any one of the three stages dies of starva- 

 tion. 



Since it is known that spotted fever is communicated from wild 

 animals to human beings by the bite of infected wood ticks and that 

 the two younger stages live almost entirely on small native rodents — 

 from which they occasionally contract the infection — it is evident 

 that- these tick hosts should be destroyed, at least around ranches. 

 The extensive damage done by the same animals to agricultural 

 interests is another important reason for their destruction. 



The chief purpose of this publication is to point out the best 

 methods of destroying these native mammals. The investigations 

 on which it is mainly based have been carried on for several years 

 in the Bitterroot Valley. Mont., by the Biological Survey in coop- 

 eration with the Bureau of Entomology and the Montana Agricul- 

 tural Experiment Station. During the seasons of 1910 and 1911 

 the author, representing the Biological Survey, worked in coopera- 



1 For detailed information in regard to the life history of the tick see Bull. 105, Bureau 

 of Entomology. 

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