FOREST INSECTS IN THE NORTHEAST 



By H. B. Peirson 



State Forest Entomologist of Maine 



'T'nii subject of forest insects and their control is an 

 ' extremely broad one in that it covers a multitudinous 

 number of conditions and insects, each of which has its 

 array of successors. Too little attention has been given 

 to the destructiveness of these insect pests and few peo- 

 ple realize that the yearly damage to our forests by these 

 insects is greater than the loss caused by fire. Neverthe- 

 less this is true. Over 8,000,000 acres of timberland are 

 destroyed yearly by insects. Reports based on actual 

 cruises show that California, between 1910-1915, lost an- 

 nually 155,000,000 feet in yellow pine alone. During a 

 period of ten years bark-beetles destroyed 1,000,000.000 

 feet of timber in the Black Hills of South Dakota. Prob- 

 ably nowhere on the continent has the damage from in- 

 sects been so great as in the forests of the northeast, 

 particularly in the spruce 

 forests of Maine. 



Years ago it was be- 

 lieved that trees commonly 

 died of old age and there 

 are many people today who 

 still hold to this belief. In- 

 vestigations have shown 

 that trees seldom if ever 

 die of old age they never 

 get the chance, the one 

 great exception being the 

 world famed Sequoias of 

 the Pacific slope, which 

 for some unknown reason 

 have been able to with- 

 stand insect attack. Nearly 

 every conifer which dies 

 will, if examined, show 

 evidence of the attack of 

 either insects or fungi, and 

 at least ninety per cent of 

 the loss is due to insects. 

 This statement refers to 

 the ever constant dying of 

 trees which yearly amounts 

 to approximately one per cent of the stand and does not 

 refer to widespread disasters as caused by fire, wind or 

 epidemics. When conditions become favorable these in- 

 sects which are ever present in the forest become numer- 

 ous enough to start an epidemic such as Maine has re- 

 cently experienced in the wholesale destruction of spnice 

 and fir by the spruce budworm and is now experiencing 

 in the destruction of spruce by bark-beetles. 



The history of past outbreaks of insects in the North- 

 east, particularly in Maine, is of especial interest in that 

 it throws much light on what may be expected in the 

 l^resent and in future outbreaks. The earliest records in 

 regard to the dying of spruce in the forests of the North- 



nURN FOLLOWING BUDWORM OUTBREAK 



Owing to the vast amount of dry wood and tops left after a 

 budworm epidemic, serious fires very often follow. 



east is found in a letter quoted by Packard. This letter 

 written in 1818, mentions great destruction of spruce 

 east of the Penobscot. Very little was written on this 

 oubreak due to the fact that at this time very little 

 spruce was being cut, white pine being the principal 

 timber tree lumbered. The next outbreak occurred 

 about 1880. The destruction wrought at this time 

 brought forth much more attention, for spruce was being 

 cut in large quantities. Such reports as "One billion 

 feet of spruce killed along Allagash and tributaries of 

 the St. John River," "great destruction of spruce in 

 North Somerset County," and that "the slump in the 

 amount of spruce coming down the rivers after the out- 

 break was very noticeable," are common. 



There is no question in the writer's mind but that each 



of these past outbreaks 

 started with a widespread 

 budworm epidemic fol- 

 lowed by bark-beetle out- 

 breaks. The last outbreak 

 of the budworm started 

 about 1910 and lasted un- 

 til 1919. This is being fol- 

 lowed by swarms of bark- 

 beetles which in many lo- 

 calities are attacking the 

 green spruce, and proving 

 a serious menace to the re- 

 maining timber. 



It is well worth while to 

 review in a few words an 

 active outbreak. In the 

 first place the budworm is 

 present at all times in the 

 spruce and fir stands of 

 northern Maine. It is 

 present in such small nun)- 

 bers that little or no at- 

 tention is called by its 

 feeding, which is limited 

 alniost entirely to the tops 

 of the taller firs. When conditions become favorable 

 which in this ca.se lueans the maturing of the fir the 

 budworm again finds an abundance of food in the sun- 

 light, and eggs are laid by the moths on the needles at 

 the tops of the fir trees that are in the sunlight. These 

 eggs, which are laid from the first to the fifteenth of 

 July, hatch in about ten days and the small cateq^llars 

 crawl into crevices in the bark beneath lichens or even 

 into the small cones where they spin a small cocoon and 

 thus pass the winter. They come out in the spring just 

 before the balsam buds open and feed for three weeks 

 or more on the foliage. An abundance of food and a 

 favorable season means that most of the caterpillars will 



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