FORESTS 



FORESTS 



343 



Insect Enemies of Woodlot Trees. Figs. 488- 

 491. 



By A. D. Hopkins. 



The insect enemies of trees in the woodlot differ 

 with the section of country and the kind of trees rep- 

 resented. In the New England states, the woodlot 

 may consist of almost pure stands of white pine, 

 mixed spruce, pine, birch and the like, maple, oak 

 and hickory ; farther south it may consist of pure 



stands of scrub 

 pine, pitch pine, 

 black locust, or 

 mixed hard-wood, 

 yellow poplar, 

 walnut, beech, 

 chestnut ; i n the 

 south Atlantic 

 and gulf states it 

 may be loblolly 

 or long-leaf pine, 

 sweet gum or 

 mixed hard- 

 woods ; north of 

 the gulf states it 

 may be mixed 

 hard -woods, with 

 oak, hickory, lo- 

 cust, box elder or 

 Cottonwood pre- 

 dominating; in 

 the Rocky moun- 

 tain region it may 

 be pine, spruce, 

 aspen or cotton- 

 wood ; toward the 

 Pacific coast, 

 scrub oak, live oak, pine or redwood ; in the North- 

 west it will consist of a different class of trees, 

 growing under very different conditions from those 

 found in any other section of country. 



Each tree and each section of the country has its 

 peculiar class of insects, requiring special methods 

 of control. It is readily seen to be impracticable 

 to discuss in a short treatise even the more impor- 

 tant insect enemies of the farmers' woodlots in all 

 sections of the country. If we take one section, 

 however, we may give some general information 

 on the character and extent of the depredations by 

 a few of the principal and more widely distributed 

 enemies, and methods for their control. 



Enemies of a special section. 



In the section east of the Mississippi river and 

 north of the gulf states, the average insect losses 

 affecting the medium- to large-sized hard-wood 

 trees of the Woodlot and small forests evidently 

 equal, or even surpass, the average losses to the 

 same class of timber by forest fires. The hickory 

 bark-beetle has killed a large percentage of the 

 hickory ; the black locust has been so badly dam- 

 aged by the borer that in some sections where the 

 conditions are otherwise most favorable for the 

 growth of this valuable tree, it is rendered practi- 

 cally worthless; the heart-wood of some of the 



Fig. 488. Work of the Uckoiy bark- 

 beetle on surface of wood beneath 

 the bark: a, primary gallery ; 6, 

 larval mines. 



finest specimens of oak and chestnut is often so 

 badly damaged by timber worms that it is value- 

 less for anything but fuel or rough boards. While 

 the pines and spruces suffer more perhaps from 

 fire than from insects, especially the young growth, 

 there are certain insects, as the white pine weevil, 

 which often cause serious damage. Thus we see 

 from these four examples alone that the insect 

 problem is by no means the least important to be 

 considered by the farmer in the management of his 

 woodlot. 



There are also local problems, like those pre- 

 sented in Massachusetts and adjoining states by the 

 gypsy moth and brown-tail moth, which are already 

 demanding attention through federal, state and 

 private effort and the publication of information. 



Controlling special cases. 



It may appear at first that the problem of con- 

 trolling the more common and widely distributed 

 insect enemies of forest trees is diificult and expen- 

 sive, when, in fact, it is often just the reverse. A 

 few special cases are cited to demonstrate this 

 point. 



The hickory bark-beetle {Scolytus quadrispinosus) 

 is a short, stout, shining, black or brownish beetle, 

 averaging about one-eighth of an inch in length, 

 which attacks the medium to large hickory trees 

 in the spring and summer, and girdles them by ex- 

 cavating egg galleries and larval mines (Pig. 488) 

 under the bark. The undeveloped brood passes the 

 w i n t e r i n the 

 bark, and the 

 matured brood 

 of adults files in 

 May to August 

 to continue the 

 depredations. To 

 control an out- 

 break of this 

 pest it is neces- 

 sary that all, or 

 at least a large 

 percentage of the hickory 

 trees within a radius of a 

 few square miles that die 

 from any cause in the sum- 

 mer, be felled and utilized for 

 fuel, or other purposes, or be 

 burned, to kill the over-win- 

 tered broods. The work must 

 be done in the period begin- 

 ning with about the first of 

 October and ending with the 

 first of May. To prevent 

 further trouble, living hick- 

 ory trees for any purpose 

 should be cut in the spring 

 and summer, so that the tops 

 and unused parts of the 

 trunks may be utilized by the 

 beetles as breeding places 

 and thus serve as traps, 

 when they can be destroyed 

 the following winter by 



Fig. 489. Locust borer 

 {Oyllene robinice), 

 TJpper figures, mahire 

 beetle : left, male; 

 right, female. Lower 

 figures, the larva, 

 showing dorsal view 

 on left and lateral 

 view on right, (Up- 

 per figures enlarged 

 slightly less than one- 

 half : lower figures 

 slightly more than 

 one-half.) 



