423 



THE SPRUCE BUDWORM 



R. C. BROWN, H. J. MAC ALONEY, P. B. DOWDEN 



The spruce budworm is a small, 

 foliage-feeding caterpillar that peri- 

 odically kills an immense amount of 

 spruce and balsam fir in the Eastern 

 States and Canada. It is serious in jack 

 pine in the Lake States, and in Doug- 

 las-fir, alpine fir, white fir, Engelmann 

 spruce, blue spruce, lodgepole pine, 

 and ponderosa pine in the West. 



It is native to North America. Rec- 

 ords of its ravages in the East date 

 from about 1805. It appeared again in 

 epidemic proportions about 1880. 



The first outbreak to be studied 

 carefully began in Quebec in 1909, 

 appeared in Maine in 1910 and in 

 New Brunswick and Minnesota in 

 1913, continued for nearly a decade, 

 and destroyed more than 250 million 

 cords of spruce and fir pulpwood. 

 About 30 million cords were killed in 

 Maine; in Minnesota, more than 20 

 million cords were destroyed. 



But all that devastation, all that de- 

 struction may be nothing compared to 

 a current outbreak in Canada that be- 

 gan to assume epidemic proportions in 

 1935. By 1944, it was estimated, 125 

 million acres in Ontario were infested. 

 In 1945, an official of a Canadian pulp 

 and paper company said, the insect 

 killed enough timber to supply all 

 Canadian pulp mills for 3 years. By 

 1947 most of the mature fir and a 

 considerable part of the white spruce 

 on an estimated 20,000 square miles 

 had been killed, with less intense dam- 

 age over a much larger area. The dead 

 trees have created a tremendous fire 

 hazard; large areas affected by the 

 budworm already have been burned. 



The memory of the previous out- 

 break in Maine and the present situa- 

 tion in Canada have caused great 

 alarm among owners of timberland and 

 officials of the pulp and paper industry 

 in the Northeast. At stake in the region 

 are nearly 19 million acres of spruce- 

 fir and more than 100 million cords of 



pulpwood. On that timber supply de- 

 pend more than 90 mills, which have 

 an annual capacity of 3 l / 2 million 

 cords, employ more than 55,000 work- 

 ers, and manufacture goods worth 

 more than 300 million dollars annually. 



BECAUSE OF THE SERIOUS THREAT to 

 the pulp and paper industry, the tim- 

 berland owners asked Congress for 

 funds to find ways to control the insect 

 and to prevent widespread damage 

 such as had occurred in Canada. The 

 funds were voted, and in July 1944, two 

 units of the Department of Agriculture, 

 the Bureau of Entomology and Plant 

 Quarantine and the Forest Service, be- 

 gan a program to study the problem in 

 all its phases and develop a plan of 

 action for the Northeast. Surveys in 

 which the States cooperated indicated 

 that few specimens of the spruce bud- 

 worm were present then in New Eng- 

 land forests. 



But in 1945 we discovered an infes- 

 tation in the Adirondacks of New York. 

 The next year we found many more, 

 and an outbreak seemed imminent. In 

 1947 and 1948, however, the popula- 

 tion of spruce budworm dropped mark- 

 edly. Over most of the area, defoliation 

 was not severe enough to cause appre- 

 ciable damage to spruce and fir. Dur- 

 ing 1945, 1946, and 1947, the insect re- 

 mained at an extremely low population 

 level in Vermont, New Hampshire, and 

 Maine. The 1948 survey showed a low 

 degree of abundance in Vermont and 

 New Hampshire but a definite increase 

 in Maine. No report of unusual abun- 

 dance of the budworm has been re- 

 ceived from the Lake States. Extensive 

 outbreaks were in progress in 1948 in 

 the southern, central, and northern 

 Rocky Mountain regions and in Ore- 

 gon and Washington. 



From 1945 to 1948 intensive studies 

 in biological and natural control of the 

 insect were conducted in New York. 



