124 



The latter, which are also confined to rodents, repeat the history of the 

 larvae, only feeding for a day or so longer, and become adults in the 

 next spring, approximately two years after the eggs were deposited. 

 The minimum period of engorgement in the adults, which feed on 

 larger animals, is ten days, and those not securing hosts may live two 

 to four years. The salient features from the standpoint of possible 

 control are that the ticks feed only on the blood of mammals, and that 

 a new host is required by each of the three stages, which only feed for 

 a few days in three successive seasons, and are only active at certain 

 times during the season. 



There are two methods of attack — eliminating the hosts so that the 

 ticks will starve, or killing the ticks on the hosts. The immature stages 

 can only be attacked by the former method, and the ground squirrel 

 is directly responsible for 95 per cent, of the ticks. An account is 

 given of the various methods of controlhng adult ticks on animals ; 

 these have already been noticed [R. A.E., B, ix. 111]. The application 

 of kerosene and lard, and turpentine and lard, has served to free animals 

 of ticks for long periods. Raw cottonseed and raw hnseed oil also 

 show considerable promise. On cattle the oil should be apphed from 

 the base of the horns to a point about halfway between the hips and 

 thighs, and about 4 or 5 fluid oz. to each animal. 



The author deals at length with the need for new investigations. 

 The chief fact underlying the proposed research is that, given equivalent 

 adult host conditions, the abundance of ticks in any localitj' is dependent 

 on the character of the vegetation or of the soil covering, as this deter- 

 mines the species of rodents and their relative abundance. The great 

 value of such investigations would be that they might show that the 

 reservoir of the disease may be controlled and the prolonged programme 

 of tick control done away with. 



ScHOPPE (W. F.). Control o£ Poultry Lice and Mites. — Montana 

 Agric. Expt. Sta., Bozeman, Circ. 95, May 1921, 8 pp., 2 figs. 

 [Received 12th April 1922.] 



This circular is a revision of an earlier one [R.A.E., B, vi, 65], 

 and has been amplified by information from other papers that have 

 already been noticed. 



Sturtevant (A. H.). The North American Species of Drosophila. — 

 Carnegie Inst, of Washington, Washington, D.C., Pubn. 301, 

 1921, 150 pp., 3 plates, 49 figs. [Received 29th May 1922.] 



This systematic study of the genus Drosophila, as occurring in North 

 America, has been made largely because the flies of this group have been 

 found very suitable for laboratory experiments, and also because there 

 has been a large number of mutations discovered in the laboratory 

 races of D. melanogaster, Meig., and it was hoped that fertile hybrids 

 might be obtained for the purpose of comparison with wild species of 

 Drosophila. This attempt has not as yet been successful. 



The more important available information concerning the Droso- 

 PHILINAE is brought together in this useful monograph, and, though 

 dealing essentially with North American species, the exotic forms are 

 incidentally dealt with. The taxonomy, anatomy, development, 

 distribution and habits of the group are presented as fully as pos- 

 sible ; only a brief survey of experimental work is attempted, but a 

 bibliography of the experimental literature is given, as well as a 

 catalogue of the described species. 



