ECONOMIC ZOOLOGY ENTOMOLOGY. 157 



A paper by J. "A. Grosbeck entitled The Mosquitoes of the Season, with notes 

 on the eggs found in the salt-marsh work is appended to the report. Culex 

 dijari was collected in the State for the first time. 



Mosquitoes and malaria in Dehra Doon, India, F. W. Thomson {Jour. Roy. 

 Army Med. Corps, 12 {1909), A'o. 5, pp. 502-508). — A list of mosquitoes inhab- 

 iting Dehra Doon and the country in the immediate neighborhood is included 

 in this account. The commonest species in the barracks were Myzomyia 

 rossii, M. culicifacies, Nyssorhyjichvs maculatus, all the Stegomyife, and Culex 

 fatigans. 



Practical information on the scolytid beetles of North American forests. 

 I, Bark beetles of the genus Dendroctonus, A. D. Hopkins ( U. S. Dept. Agr., 

 Bur. Eut. Bid. S3, pt. 1, pp. 169, pis. 2, figs. i02).— This work deals with the 

 more practical results of extensive investigations conducted between 1891 and 

 1908, and thereby supplements Technical Bulletin 17, pt. 1, previously noted 

 (E. S. R., 21, p. 557). A detailed account is given of the distribution, seasonal 

 history, habits, economic features, and methods of control, so far as known, 

 of 23 species. 



The investigations are said to have clearly shown that some of the species 

 of this genus of beetles are the most destructive enemies of the coniferous forest 

 trees of North America, and it is considered probable that if the timber de- 

 stroyed by these insects in the United States in the past .50 years were living 

 to-daj' the stumpage value would be more than .$1,000,000,000. In regard to the 

 possibilities of control the author reports that experiments and practical de- 

 monstrations make it clear that wherever private, state, or national forests are 

 under organized management for fire protection and economic utilization, the 

 control of these insects is often a less difficult and less expensive problem than 

 that of controlling forest fires. 



All of the species of Dendroctonus studied have demonstrated their ability to 

 attack healthy trees and kill them whenever the individuals of a species occur 

 in suflicient numbers to overcome the resistance of the tree. In combating these 

 pests success depends largely on a knowledge of the proper time to begin and 

 end certain timber-cutting or barking operations for the destruction of the 

 broods of the beetles. The natural enemies are considered under the headings 

 of insects, birds, diseases of the insects and diseases of the trees. 



The western pine beetle {Dendroctonus brevicornis) attacks western yellow 

 pine and sugar pine and is destructive to living timber in the mountains of 

 California and northward and eastward to Washington and Montana. It is 

 especially destructive to the western yellow pine in central Idaho and in the 

 mountains of the higher valleys of eastern Washington, Oregon, and California. 

 In localities where it is known the principal clumps of infested trees should 

 be located from September to March, and the infested bark on the main trunk 

 and larger branches removed and burned or the logs converted into lumber 

 and the slabs burned, between October and June 1. 



The southwestern pine beetle {D. barberi) attacks western yellow pine in 

 southern Colorado and Utah, and in the mountains of Arizona, New Mexico, 

 western Texas, and northern Mexico. The methods of control are similar to 

 those of the western pine beetle. The roundheaded pine beetle {D convexi- 

 frons) attacks western yellow pine from southern Arizona to northern New 

 Mexico and southern Colorado. As this species is usually associated with 

 others its specific relation to the death of trees is doubtful. The southern pine 

 beetle {D. frontalis) attacks all of the pines and spruces of southern Pennsyl- 

 vania southward into Florida and westward into eastern Texas and Arkansas. 



