52 



NEW YORK STATE ML'SEl'.M 



of other insects on our maples, specially the depredations of the so called 

 maple worm or forest tent caterpillar, Malacosoma disstria Hiihn., 

 are from time to time pictured in most j^dowing colors, and while these other 

 pests undoubtedly cause much injury, the fact remains that the sugar maple 

 borer is quietly and unobtrusively carrying on its deadly work and in a 

 series of years probably kills more of these popular shade trees than any 

 other insect pest. In almost every city and village where sugar maples 

 adorn the roadsides, evidences of the work of this borer are very apparent 

 and in many of these places dead or nearly ruined trees are by no means 

 scarce. The unthrifty condition of these maples is frequently attributed to 

 drought, fungous diseases, leaking gas, pavements impervious to water, etc., 

 whereas, in fact, the true depredators are gnawing within the trees. 



Character of the injury. Unlike many borers, this insect attacks trees 

 in full vigor. The powerful, legless grub confines its operations largely to 

 the inner bark and sapwood, and as it runs a burrow several feet long in one 

 season, and as one borer will frequently work transversely half around a tree 

 some 1 8 inches in diameter, the dangerous character of this pest is at once 

 apparent. The bark over the burrow, be it either a longitudinal or a trans- 

 verse one, dies and the growing tissues forming underneath in the natural 

 process of healing push the dead bark out, cause it to break ami in the 

 course of a year or two an ugly, naked scar is produced. A large patch of 

 bark may be killed by several borers working near each other or possibly 

 by one doubling back and forth, and the result is a large, unsightly area of 

 e.xposed wood. The injury produced by a transverse burrow is shown at 

 figure 2, and a blasted area resulting from the doubling of a borer or of the 

 work of several near together is shown at figure 3. Two or three borers in 

 the same trunk are very likely to nearly girdle a tree, if they do not kill 

 it outright. Infested maples frequently have one or more large branches 

 killed by this ])est. The base of the limb is girdled in the same way as the 

 trunk, the first intimation of trouble in this manner usually being a sudden 

 wilting of the foliage, followed by the leaves drying up and falling. I his 

 borer displays a marked preference for the base of large limbs and 

 adjacent portions of the trunk. 



