772 



AMERICAN FORESTRY 



cume disfigured and finally often broken from tne tree. 



The eggs of the leopard moth are deposited in masses 

 of several hundred each in the crotch of a branch or in 

 crevices in the bark. On hatching, the young caterpillars 

 b^in their work in the smaller branches, feeding on the 

 plant tissues and rapidly increasing in size until at 

 maturity they reach a length of two inches. When partly 

 grown, the caterpillars leave the small branches where 

 they begin their work and nigrate to larger ones or in the 

 case of a comparatively small tree, to the main trunk. 

 Here each caterpillar excavates a cavity about an inch 

 broad and several inches long just under the bark. It then 

 b^ins to work toward the heart wood leaving a channel 

 one-half inch in diameter and about six inches long. The 

 writer has personally observed a partly grown caterpillar 

 of the leopard moth in the act of boring its way through 

 the solid wood into the main trunk of a silver maple. 



After entering the tree the hole, through which the 

 caterpillar has entered, is entirely concealed by a web 

 which is spun for the purpose so that it is almost im- 

 possible to detect the presence of the insect except by 

 the characteristic wood pellicles which are thrown from 

 the burrow. This is usually done at night after which 

 the opening is again closed. 



It requires two years for the leopard moth to complete 

 its life cycle. The caterpillar remains in a dormant 

 condition during the first winter and resumes feeding the 

 next spring, attaining its full size toward the end of the 

 second summer. A second winter is passed in the larva! 

 stage and the next spring the pupae are formed near the 

 entrance which later becomes the exit. The adult moth 

 emerges in early summer, being most abundant in late 

 June or early July. Being nocturnal in its habits the 

 adult- moth is not so frequently seen. 



As previously stated, the artificial control of this in- 

 sect is not easily effected. Some beneficial results can, 

 however, be accomplished in the case of a comparatively 

 young tree when the attack is in the main trunk or larger 

 branches within easy reach. When its presence has been 

 detected by the presence of the wood pellicles on the 

 ground underneath, on account of the large size of the 

 cavity the caterpillar can be drawn from its burrow by 

 means of a wire provided with a hook or barb at the 

 end. Or the caterpillar can be killed by injecting a 

 poison, such as bisulfid of carbon into the burrow. While 

 this might seem to be a rather crude or slow process, 

 when we recall the fact that each adult female when 

 she emerges is able to deposit several hundred eggs, the 

 effectiveness of this remedy in checking the spread of the 

 insect is more easily appreciated. After removing or 

 killing the caterpillar the wound should be treated so 

 as to prevent the decay which is likely to follow. 



The locust borer (Fig. 6) is another deep- wood borer 

 which is responsible for a great deal of damage, but 

 fortunately, its restricted habits render it much less de- 

 structive than the preceding. The insect attacks only the 

 black locust {Robinia) ^b\lt here it is capable of such devas- 

 tation that it has rendered impracticable the cultivation of 

 this tree either for ornamental or for commercial purposes. 



The keeping qualities of the wood of the black locust 

 are such as to recommend its growth for various pur- 

 poses where great resistence to decay is required, espe- 

 cially for railroad ties. Consequently one railroad com- 

 pany, a few years ago, under supposedly expert advice, 

 planted more than two millions of seedlings to be grown 

 for ties. In the course of a few years the entire planta- 

 tion was ruined by the attacks of this and other insects 

 so that the project had to be abandoned. Photographs 

 of this plantation might easily be mistaken for those of 

 a bullet-riddled forest from a European battlefield. 



The adult stage of the locust borer is a large, beauti- 

 fully striped beetle nearly an inch in length, the black 

 wing covers with their yellow stripes giving them a very 

 attractive appearance. It is a very active insect and may 

 often be found flitting about goldenrods and other bright 

 colored flowering plants where it feeds rather sparingly 

 on the pollen from the flowers and where undoubtedly 

 its own bright colors serve as a device to protect the 

 beetle from being detected by its enemies. The beetle 

 is short lived although apparently very optimistic and 

 dies soon after completing the process of reproduction. 

 After mating the female soon flies back to the locust 

 tree where her eggs are deposited in the soft tissue just 

 underneath the bark. The young larvae soon hatch and 

 burrow into the wood where, unlike the leopard moth, 

 they complete their life cycle one year from the time the 

 eggs are deposited. The larva, when full grown, is a white 

 grub about an inch in length and a voracious feeder. 



The channels are about the size of an ordinary lead 

 pencil. The wood which is chewed up, is passed through 

 the body, the digestible parts taken out, and the refuse 

 deposited in the form of rather coarse sawdust-like par- 

 ticles. This partially digested wood is thrown out in 

 such large quantities as to form little heaps at the base 

 of the tree when badly infested. The wood is often so 

 thoroughly honey-combed by the grubs that the entire 

 tree is distorted and the branches easily broken from the 

 tree by the wind. 



Since boring insects are difficult to combat by arti- 

 ficial means, it follows that we must depend largely on 

 their natural enemies for their control. The most im- 

 portant of these natural enemies are the birds. Some 

 one has said that the woodpeckers are the natural pro- 

 tectors of our forests and woodlands and certainly no 

 bird is better equipped for warfare against boring insects. 

 With its chisel-like beak, its sharp barbed tongue and its 

 keen sense of hearing, it is sure death to the shallow 

 boring insect. One block of hemlock about ten inches 

 long and eight inches in diameter showed upwards of a 

 hundred shallow holes made by woodpeckers in search 

 of insects. Just how many were obtained it is difficult 

 to say but knowing the habits of the bird it is safe to 

 say that the work was not in vain. 



While the woodpeckers go after the grubs the fly- 

 catchers prey upon the adult. Too much cannot be said 

 in favor of offering protection and encouragement to our 

 "feathered friends" upon whom we must depend very large- 

 ly for protection against the ravages of the boring insects. 



