238 THE ROYAL SOCIETY OF CANADA 



the host for the following periods: Larva, 2-8 days; nymph, 4-11 

 days; the adult female feeds from 5-15 days, the male feeds from 

 3-4 days before seeking the female. Metamorphosis from egg to larva 

 lasts in Montana from 14-25 days; from larva to nymph in British 

 Columbia 24-38 days; from nymph to adult from a minimum of 12 

 days to a maximum of 170 days in Montana, or 32 days in summer 

 and 84-94 days in winter in British Columbia. Oviposition, reckoned 

 from the day the female abandons the host, begins in Montana 6-13 

 days in warm weather and 41 days when it is cool. The female may 

 survive 1-14 days after the eggs are laid. The number of eggs laid 

 by one female may vary from 2,500 to 7,140, 4,000 being about the 

 usual number. Longevity. Unfed larval ticks usually die in 30 days, 

 but they may survive up to 117 days; unfed nymphs may live over 

 300 days; adults captured in the spring on vegetation survived 

 unfed for 413 days, after fasting for 365 days they readily attached 

 themselves to a host. The life cycle may be completed in 68 days 

 under most favourable conditions ; the time usually required is 2 years, 

 but 3 years may be required. The seasonal history in Montana is as 

 follows: the unfed nymphs and adults hibernate; they find hosts from 

 March to July, during which time they attack man ; the females which 

 feed in the spring lay eggs which lead to adults in September. Nymphs 

 occur on small wild mammals in March to July inclusive. These 

 individuals hibernate as unfed adults. The adults occur on large 

 wild and domesticated animals and on man, but the immature stages 

 rarely if ever occur on other than small animals. 



Literature. 

 The following list contains certain works additional to those 

 referred to in the text with a view to assisting those desiring further 

 information on North American ticks. 



Banks, N. A Revision of the Ixodoidea or Ticks of the United States. U. S. Dept. 

 Agriculture, Bur. Ent., Tech. Ser. Bull. No. 15, 61 pp., 10 pis. 1908. 



Bishopp, F. C. and H. P. Wood. The Biology of Some North American Ticks of the 

 Genus Dermacentor. Parasitology. Vol. 6, pp. 153-187, 1 fig., 3, pis., 1913. 



Hadwen, S. On "Tick Paralysis" in Sheep and Man following bites of Dermacentor 

 venustus, with notes on the Biology of the Tick." Parasitology, Vol. 6, No. 3, 

 pp. 283-297. October, 1913. 



Hadwen, S. and Nuttall, G. H. F. Experimental "Tick Paralysis" on the Dog. 

 Parasitology, Vol. 6, No. 3, pp. 298-301, Oct. 1913. 



Hadwen, S. Reports of the Veterinary Director General, Department of Agriculture, 

 Ottawa, Canada, for the Years ending March 31st, 1912, 1913 and 1914 respect- 

 ively. In Report for 1912, see pp. 93-99; in Report for 1913, see p. 80. 



Hewitt, C. G. Reports of the Dominion Entomologist, Department of Agriculture, 

 Ottawa, Canada, for the Years ending March 31st, 1911 (pp. 225-226); 1912 

 (p. 183); 1913 (p. 512.) 



