THE SPRUCE BUDWORM 



Ey R. C. Brown, senior entomologist, 



Division of Forest Insert Investigations, Bureau of Entomology and Plant 



Quarantine, Agricultural Research Administration 



A Serious Threat to Our Spruce-Fir Forests 



Another serious outbreak of the spruce budworm (Archips fumi- 

 ferana (Clem.)) is now occurring in the Provinces of Ontario and 

 Quebec, Canada, and threatens the spruce-fir forests of New England, 

 New York, and the Lake States. This outbreak in Canada attracted 

 attention in 1937 and has since increased in area at an alarming rate. 

 Surveys made by the Division of Entomology of the Dominion of 

 Canada Department of Agriculture show that by 1943 about 90 percent 

 of the balsam fir and 50 percent of the spruce had been killed on 12.000 

 to 15,000 square miles. In addition, an area estimated at 30,000 square 

 miles now sustains a medium infestation where 5 to 10 percent of the 

 timber has been killed. There are also other vast areas where light 

 defoliation has been noted but where as yet little death of timber has 

 occurred. 



During the widespread outbreak of 1910-20 which occurred in 

 Quebec, New Brunswick. Maine, and northern Minnesota, it was esti- 

 mated that over 225 million cords of pulpwood was destroyed. The 

 history of this outbreak is a constant reminder of the danger that 

 exists throughout our northern forests when heavy outbreaks are in 

 progress across the border. No outbreaks of this insect are known 

 to occur at the present time in the spruce-fir forests of the northeastern 

 part of the United States. A few adults were taken at light traps, 

 however, and occasional larvae were seen in Maine during li>43. 



A biological race of the spruce budworm which prefers jack pine 

 occurs in the Lake States. This form has been causing noticeable 

 defoliation in Minnesota for several years, and in 1943 heavy defolia- 

 tion was observed on the Superior National Forest in that State. 



Because of the possibility that some undetected outbreak may exist 

 at the present time in this country, every effort should be made to 

 survey thoroughly the spruce-fir and jack pine forests in the States 

 bordering Ontario and Quebec. Ynd because of the vast area in- 

 volved, it will be necessary to enlist (he help of all agencies which have 

 men operating in the spruce-fir and jack-pine region and to supply 

 these men with adequate information to enable them to recognize the 

 insect, so that they may report their findings to the proper authori- 

 ties. The purpose of this leaflet is to provide a description oi the 

 spruce budworm and of its feeding so that everyone interested in the 

 preservation of our northern coniferous forests may become familiar 

 with the characteristics of this dangerous enemy. 



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