14 



COKE AND NUT WORMS. 



The cones and fruit of pine, spruce, and other conifers and nut- 

 bearing trees are often infested by small caterpillars which prevent 

 the development of the cones and seeds. 



GALLS. 



There are certain gall insects which attack cones and cause a 

 deformed development either of the cone or the seeds. 



INSECT INJURY TO FOREST PRODUCTS. 



Insects injure various kinds of crude and finished forest products 

 and reduce their value or render them entirely worthless. 



INJURY TO FRESHLY CUT PRODUCTS. 



This is caused by a class of insects which attack freshly sawed lum- 

 ber, square timber, stave bolts, etc. (See Timber beetles and Timber 

 worms.) 



INJURY TO DRY AND SEASONED PRODUCTS. 



This is caused by a class of insects which attack the sapwood of sea- 

 soned lumber, handles, spokes, and the like; also tan bark. (See 

 Powder-post beetles.) 



BENEFICIAL INSECTS. 



jpredaceous insects. — This is a class consisting of beetles, wasps, and 

 true bugs, which feed on injurious insects and are often very benefi- 

 cial in reducing the numbers of some of the more destructive kinds. 



Parasitic insects. — This is a class which is represented by the four- 

 winged and two-winged flies, the larvae of which either live within the 

 bodies of the larvae and adults of injurious insects or attach them- 

 selves to the bodies of the larvae and pupae and kill them. This class 

 is a very extensive one, and is of enormous benefit in reducing the 

 numbers and keeping in check the ravages of the. destructive species. 



METHOD OF PREVENTING LOSSES. 



The methods of preventing losses from depredations by forest insects 

 consist mainly in the adoption of improved methods of forest manage- 

 ment, based on a knowledge of the life histories and habits of the 

 primary and, secondary enemies of the trees and the natural enemies 

 of the insects. Recommendations for the application of any method 

 must be based on a knowledge of the special insect or group of insects 

 found to be primarily to blame for the losses, and must necessarily 

 vary in the details to suit the requirements of local conditions, differ- 

 ent kinds of insects, different kinds of trees, and different kinds of 

 forest products; it is therefore difficult and scarcely advisable to give 

 any general recommendations in this connection for preventing losses. 

 This will be brought out in future publications, reports, and special 

 correspondence. 



