APPENDIX. 359 



arbor vitae, etc., among shade trees. As house i^ests they are ti-oublesome 

 from their presence merely in their efforts in the fall to find safe hibernating 

 quarters and occasionally in their spring migrations in search of suitable 

 breeding grounds. 



ORIGIN AND DISTRIBUTION. 



Attention was first drawn to this mite in 1879, at Washington, D. C, from 

 its occurrence on the trees in the department grounds and also on clover on 

 lawns. It has since been reported from numerous localities, from Massachu- 

 setts to California. Northward it occurs in the east in northern New York 

 and Canada. East of the Mississippi it has not been reported in the southern 

 tier of states, the southernmost records occurring in Tennessee and North 

 Carolina. 



On the Pacific Coast it is known from San Diego, in California, to East 

 Sound, in Washington ; and at Las Cruces, New Mexico, it is a serious fruit 

 pest. In the Sierra Nevada Mountains in California and in the Rocky 

 Mountains in Montana it has been found at elevations of from seven thousand 

 to eight thousand feet. 



It is remarkable, therefore, for its ability to exist under marked differ- 

 ences of temperature and elevation. Its wide distribution and its occurrence 

 in situations remote from settlement indicate that it is a native species. It 

 was first characterized scientifically by H. Garman in 1885, who proposed ior 

 it the common and Latin name by which it is now known. 



HABITS AND LIFE-HISTORY. 



The wide range of this insect and the different climatic conditions under 

 which it exists lead, as might be expected, to certain variations in its life- 

 history and habits in different localities. In the more northern regions of 

 its occurrence and in the higher elevations it winters in the egg state, the 

 last brood, if it may be so called, maturing in the fall, and depositing eggs 

 on branches and trunks of trees sometimes in sufficient numbers to entirely 

 cover the bark two or three layers deep. In 1889 we received a mass of 

 these eggs several layers deep on a piece of bark which the sender states 

 was from an area of at least fifty square feet of eggs on the south side of 

 trunks of cotton woods growing' at an elevation of from six thousand to eight 

 thousand feet. This was in the Sierra Nevada Mountains, Tuolumne County, 

 c California, and we have had a similar account, with specimens, from Mc- 

 Carthy Mountain, in Montana, at about the same elevation. In the middle 

 and eastern states, where the eggs are frequently found on fruit trees, they 

 are usually confined to the crotches and branches and are not nearly so 

 abundant. 



In the colder regions, where the winter is passed in the egg state, the 

 issuance of the j'oung mites the following spring- varies from May until the 

 middle of June, depending on the character of the season. In the warmer 

 regions — as. for instance, in the latitude of Washington — the mites begin to 

 be noticeable on foliage and grass in May or earlier, and enter their hiber- 

 nating quartei'S early in October, in crevices of fences or walls or under the 



