2 MISC. PUBLICATION" 74, U. S. DEPT. OF AGRICULTURE 



much attention is given, have an important bearing on brood de- 

 velopment, and their study is throwing considerable light on the 

 causes underlying the rise and fall of bark-beetle epidemics. Re- 

 sults have already been obtained which will have an application in 

 timber-sale regulations, logging operations, and slash disposal. In 

 certain cases, it has been possible, as a result of these researches, to ^- 

 predict the decline of epidemics and thus to save considerable money 

 that might otherwise have been expended needlessly in direct control. 

 These studies are centered on the national forests in California, 

 Oregon, Montana, Arizona, Colorado, and North Carolina. 



As the stumpage value of timber increases in the Western States, 

 the protection of the great stands of mature timber from these bark- 

 beetle losses constitutes an ever-growing problem. A considerable 

 part of the funds appropriated is utilized in rendering service to 

 agencies cooperating in protection from this class of insects. This 

 service consists largely in the direction and administration of the 

 technical features of control projects against tree-killing bark beetles 

 as well as in the analysis of the results. In this work close coopera- 

 tion is maintained with the Forest Service, the National Park Serv- 

 ice, the Office of Indian Affairs, and private owners. At the request 

 of these organizations or individuals surveys are made of beetle- 

 infested areas and recommendations given as to the advisability of 

 control measures and as to the methods to be employed. Occasion- 

 ally these projects cover enormous areas and involve very complex 

 administrative details. 



Field laboratories for the regional administration of these inves- 

 tigations are maintained at Coeur d'Alene, Idaho, and at Palo Alto, 

 Calif. From four to six additional temporary bases are in use 

 during the field season. 



INSECTS INJURIOUS TO FOREST PRODUCTS 



From a monetary standpoint, because of the higher values in- 

 volved, insects destructive to forest products take an even greater 

 annual toll than do the bark beetles. There are a great number of 

 insects destructive to all forms of wood products from the green 

 felled tree to the finished seasoned article. Much time and labor 

 have been devoted to the development of methods for preventing 

 damage to material of this character. In many cases all that is nec- 

 essary for adequate protection is to make simple alterations in the 

 methods of handling the material in the woods, or at the mill or 

 warehouse.' Suggested modifications of building codes to insure in- 

 sect-proof construction are being widely adopted (87). Again, 

 repellent sprays or dips are effectively employed, or the wood is im- 

 pregnated with chemicals that ward off insect attack. Two experi- 

 mental grounds are maintained — one at East Falls Church, Va., and 

 the other in the Canal Zone, Panama — where chemicals and wood ^ 

 preservatives are tested for efficiency against wood-boring insects. W 

 The Forest Products Laboratory of the Forest Service, at Madison, 

 Wis., treats wood samples with preservatives to be tested at these 

 experimental grounds. Cooperation is maintained, also, with many 

 organizations interested in wood preservation, 



