ENTOMOLOGY 309 



over one-eighth of an inch in diameter, in the solid wood, and the 

 caterpillar is white, or nearly so, with short, stiff hair on the surface. 

 It comes to maturity in spring, and some time during the latter part 

 of May or June forms its pupa near the outer surface of the trunk. 

 When ready to change to the adult stage, the pupa wriggles out for 

 about half its length, just as the pupa of the leopard moth does, and, 

 usually very early in the morning, the moth emerges. This is rather 

 a handsome little creature, yellow with red trimmings and bandings, 

 the wings thin and transparent. It is one of the clear wings and 

 looks more like a wasp than a moth. Sometimes maples are in- 

 fested by a large number of these insects, but experience indicates 

 that little real harm is done to the trees, provided water does not get 

 into the holes to cause decay. The borings are in the heart-wood 

 only, and as the heart-wood has little to do with the actual nourish- 

 ment of the tree, there is no immediate weakening. Where the 

 insects are observed in numbers it will pay to whitewash the trunks 

 several times during the season. This will be effective first, by re- 

 pelling the moths that would otherwise oviposit on the trunks ; and, 

 second, it will cover over or partly fill the smajl holes that have been 

 made by the insects. A tree once infested will, under ordinary cir- 

 cumstances, remain infested, and there seems to be an individual 

 attraction that does not extend to even neighboring trees of the same 

 species. (Bui. 181, N. J. E. S.) 



INSECTS CAUSE THE DEATH OF TREES. 



It has been conclusively demonstrated that certain species of in- 

 sects are the direct or primary cause of the death of forest trees of 

 all ages, and that from time to time they multiply to such an alarm- 

 ing extent that their depredations assume the character of a de- 

 structive invasion, which results in the death of a large percentage 

 of the best timber over thousands of square miles. 



There are many species of barkbeetles which prefer to attack 

 matured and healthy trees, and there are many examples of whole 

 forests of century-old trees having perished from the girdling effect 

 of the mines of the beetles, which are extended in all directions 

 through the inner living bark on the main trunks of the trees. In- 

 deed, we find among these bark-boring beetles the most destructive 

 insect enemies of North American forests. Some notable examples 

 of the depredations of these 'barkbeetles are given below. 



The Southern Pine Beetle, In 1890-1892 a destructive inva- 

 sion of the southern pine beetle extended from the western border of 

 West Virginia through Maryland and Virginia into the District of 

 Columbia, northward into southern Pennsylvania, and southward 

 into North Carolina. In this area, aggregating over 75,000 square 

 miles, a very large percentage of the mature and small trees of the 

 various species of pine and spruce was killed by this beetle. In many 

 places in West Virginia and Virginia nearly all the pine trees of all 

 sizes on thousands of acres were killed, while shade and ornamental 

 trees within the same area suffered the same as those in the forest. 

 Since 1902 this barkbeetle has been more or less active in the South- 

 ern States from Virginia to Texas, and in some localities and during 



