PROTECTION AGAINST FOREST INSECTS 



By the Division Forest Insects, Bureau of Entomology 



The importance of insect activities in the growth and development 

 of the forest from the time the trees are planted until they are harv- 

 ested, and even to the products after they are put to use, has already 

 been pointed out. To briefly recapitulate, insects cause enormous 

 losses in mature stands of timber which are being held in reserve for 

 future needs. They lower the yields and affect the rate of growth of 

 developing stands. They frequently change the composition of the 

 forest to such an extent that complete reshaping of the plan of man- 

 agement is necessary. They create serious fire hazards and take a 

 varying toll from crude and finished forest products. On these grounds 

 the consideration of insects in the forest is primarily a matter of 

 protection to be secured through the early detection and suppression 

 or the prevention of insect outbreaks, but also of equal if not greater 

 importance is the matter of the necessary research for developing this 

 protection. The ways and means of obtaining more adequate results 

 in protection from forest pests is discussed in some detail as follows: 



1 . The prompt control of forest insect outbreaks when such control 

 is economically sound in the broadest sense must be provided. 



Just when, where, and how to do control, and at the same time 

 secure maximum protection consistent with the economic or aesthetic 

 values at stake, is the key to the entire problem. 



The policy of letting nature work things out in here own way has 

 some merit. Such a course of action at least involves a minimum of 

 effort and cost. This policy of " letting nature take its course" is in 

 fact the one that has been followed too often, with results that are 

 all too evident. If we accept this as a course of action, we must also 

 accept the probability of slow or sudden depletion of the older forests, 

 which as they stand today are ripe and ready for the beetles. If we 

 are willing to do this and wait for nature to replace these losses by 

 the slow process of growing a new crop of trees, then the matter of 

 taking any further steps to expand our present efforts can be dropped 

 from consideration. 



On the other hand if we were to launch out upon the policy of com- 

 bating all threatening barkbeetle infestations everywhere, the cost 

 would be enormous. One million dollars would be a very conservative 

 estimate of what could be spent to advantage in California alone dur- 

 the present winter and spring for the very good purpose of killing 

 beetles that are destroying timber of high value; and in the lodgepole 

 pine forest around Yellowstone National Park over $2,000,000 could 

 be spent this spring. Such expenditures should of right be carefully 

 questioned from all angles, and the plans for any large control projects 

 governed both by economic considerations and the entomological 

 factors which involve the prospects for successful results. Intelligent 

 planning should therefore underlie the expenditure of both public and 

 private funds for control jobs of this character. 



There are two distinct classes of timberlands needing protection 

 from insect pests those where a present or future commercial value is 



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