22 REPORT OF THE COMMISSIONERS OF 



Plagionotus speciosus Say. 



Sugar maples along the roadsides in the state of New York probably have no 

 more serious insect enemy than this pernicious borer. The attacks of other insects 

 upon our maples, specially the depredations of the so-called maple worm or forest 

 tent caterpillar, Clisiocampa disstria Hiibn., are from time to time pictured in most 

 glowing 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 sap 

 wood, 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 eighteen 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 transverse one, dies and the growing tissues forming 

 underneath in the natural process of healing push the dead bark out, cause it to 

 break and 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 exposed 

 wood. The injury produced by a transverse burrow is shown at figure 7, and a blasted 

 area resulting from the doubling of a borer or of the work of several near together is 

 shown at figure 8. 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 limbs killed by this pest. 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. 



Description. The parent insect is a beautiful stout beetle about one inch long. 

 It is black, brilliantly marked with yellow, as represented at figure 4 of plate 3. The 

 borer or larva is a whitish, flattened, footless grub with brownish mouth parts. Small 

 ones (Plate 3, figure 2), about one half inch long, are found in September just under 



