INSECT ENEMIES. 55 



INSECT ENEMIES OF THE WHITE PINE, 

 By F. H. CHITTENDEN, Division of Entomology. 

 INTRODUCTION. 



Of all coniferous plants, perhaps none are more subject to insect attack than the White Pine. 

 Upward of a hundred species are reported to affect this tree, and a careful compilation of all 

 known species would probably add many more to this list. The more important are found in the 

 order Coleoptera, and of these the cylindrical bark-beetles of the family Scolytidaj hold the highest 

 rank. Most of the Scolytidse live within the cambium of dead or dying trees, but a few penetrate 

 the solid wood, and several forms, when excessively abundant, do not hesitate to attack healthy 

 growth. Numerous other Coleoptera belonging to the families CerarnbycidiB and Buprestidae 

 similarly infest the White Pine, but are for the most part secondary in the nature of their attack, 

 and will therefore require only passing mention. One species, however, the white-pine weevil 

 (Pissodes strobi Peck), is a pest of_the_jaQSi_pejuiciaus. type: In addition to the bark-boring and 

 wood-boring insects, several species infest the roots, some only the branches j?r "twigs, some 'the 

 cones, and others injure growing trees by defoliation.^ The leaf-feeding species comprise the larvaj 

 of several sawtties, the caterpillars of numerous moths, and a number of beetles. Various species 

 of plant-lice and scale insects also occur upon the leaves, and often the limbs and trunks of trees 

 are injured by them. 



Most of our injurious forest insects are native to this country, in which respect they diifer 

 markedly from those which affect field and garden crops. Only such species as experience has 

 shown to be more or less injurious either to living trees or to cut timber will be considered in 

 this paper. Some few forms that have not been recorded on White Pine are mentioned, as it is 

 more than probable that they are capable of injury to this tree. The majority, however, have 

 been observed on White Pine. 



In the preparation of the present paper the writer has drawn freely from the published works 

 of Packard, Fitch, and Hopkins, as well as from personal experience in pine forests, particularly 

 of New York. 



THE DESTRUCTIVE PINE BARK-BEETLE. 



The last decade witnessed very extensive destruction of pine and spruce forests in portions of 

 the United States east of the Rocky Mountain^s^-Tlie principal injury, which dates from about the 

 year 1888, has been attributed to the so-called destructive pine 

 bark-beetle (Dendroctonus frontalis Zimm.), one of a genus of six 

 described species, all of wide distribution and all destructive to 

 the Couifene. It is quite possible that some predisposing 

 agency had first caused a weakened condition of the trees in the 

 infested districts, but it is fairly certain that this species of beetle 

 was responsible for much injury. The infested area observed 

 comprised the pine and spruce forests from Maryland in the 

 North to and including North Carolina in the Sooth, an area Fia . s ._ DendnctonutfrontaKs: a , dor8alvi ew 

 estimated at upward of 10,000 square miles in extent. In same of beetle; &. lateral view-euiarged about six 



. . , , times [ c. antenna greatly enlarged (author's 



sections entire forests were killed. illustration). 



The accompanying illustration of this species (fig. 5) will 



enable its recognition. ^It ranges from reddish to dark brown in color, and measures about one- 

 eighth of an inch in length, being the smallest species of its genus. Its credited distribution 

 includes Lake Superior to Georgia, and it is recorded also from Arizona and California. The 

 adult beetle appears some time in May_, the date depending upon season and locality, bores into 

 living trees and its larvas develop binder the green, sappy barb^Copious quantities of turpentine 

 exude from the holes made by the beetles and dry in masses upon the bark. The manner of work 

 of the larv;e in great numbers beneath the bark produces about the same effect as that of girdling, 

 thus cutting off the flow of sap, the natural supply of plant food and moisture, greatly weaken- 

 ing and eventually killing the trees. The first outward manifestation of injury is the accumu- 

 lated masses of pitch, followed by the leaves turning yellow and then red, as though scorched 

 by fire. 



