April, '13] BISHOPP AND KIXG: SPOTTED FEVER TICK 205 



It has been supposed that different stages of ticks are probably 

 carried into the winter quarters of ground squirrels and other animals. 

 There seems little doubt that a few larvae and nymphs are still attached 

 when the animals enter hibernation. Other species of ticks have been 

 found in considerable numbers in burrows of animals during the sum- 

 mer and in one instance Mr. C. Birdsej'^e found a two-thirds engorged 

 female of Ixodes cequalis Banks in an underground nest of Citellus 

 beecheyi on Februarj^ 25, 1911, at Modesta, Cal. With a view of 

 determining if specimens of the spotted-fever tick are to be found in 

 •the winter nests of ground squirrels, one of the authors (King) had a 

 number of squirrel burrows dug up during the first part of October 

 1910, about one and one-half months after the time of hibernation. 

 No hibernating squirrels were found but forty nests (probably summer 

 nests and containing live mites and fleas) were secured and immedi- 

 ately placed in tick proof sacks. The contents of twelve of these 

 nests were thoroughly examined and the sacks containing all the nests 

 were searched without finding any ticks. Two other nests which had 

 undoubtedly contained hibernating squirrels a few days previous and 

 which were found by following fresh badger diggings were also exam- 

 ined with the same negative result. For comparison with this several 

 quarts of trash from around the entrance of one burrow was sacked on 

 September 26. By searching only the top of the sack two adults 

 and four nymphal ticks, which had crawled from the trash, were 

 found. 



Life History 



Records made by one of the authors (King) in the Bitter Root Valley 

 present some variations, from those published heretofore, in the 

 longevit}^ and the developmental periods of different stages of this 

 tick. A few of the records are here given. The greatest longevity of 

 larvae previously recorded was 117 daj's. This record was made in 

 1910. Larvae hatched in July and August, 1911, went through the 

 winter, and in a number of lots were still aliVe when last observed on 

 June 11, 1912. On May 16, 1912, some of these were taken from the 

 outdoor tubes in which they were kept and sent to Dallas by Professor 

 Cooley. These attached and engorged readily when applied to guinea 

 pigs at Dallas, Texas, on May 22. The maximum longevity in these 

 lots exceeded 317 days. It was observed that some larvae had died 

 before the advent of cold weather in the fall of 1911. 



The first two and the last records given in the following table were 

 made on ticks kept in glass cylinders with gauze tops and kept out of 

 doors in partial shade. The third record was made on ticks kept in the 

 same kind of container but in the open field. The other three lots were 



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