8 SOME INSECTS INJURIOUS TO FORESTS. 



the beetles by means of a bait of some poisoned substance which would 

 be attractive to them. 



On May 23, 1905, it was found that the locust trees of all sizes in 

 the open and in dense thickets along the old canal on Arlington Farm, 

 Virginia, were thickly infested with the borers, which were all in the 

 wood and ranged in size from quite small to nearly full grown. The 

 ground around some of the trees in the open and on the borders of the 

 groves was found to be covered with the sawdust borings to the depth, 

 in some cases, of an inch or more, and the larvae could be distinctly 

 heard at work in the wood. Some of the young trees had been literally 

 honeycombed and were broken off at the ground, others had many 

 branches broken and hanging by the bark or fallen from the tree, 

 and some other trees had the leaves turning yellow and d}^ing, while 

 one isolated tree in a field had failed to put forth leaves on some of 

 the branches. Some infested branches cut on this date and placed 

 in a box in the laboratory were found on July 12 to contain fully 

 matured adults, and on July 20 they began to emerge, thus showing 

 that the larvae will complete their development in the wood after it 

 is cut from the tree and becomes perfectly dry. Indeed, this record 

 shows that the dry condition contributes to the rapid development 

 of the insect, for on the same day (July 20) on which the beetles were 

 found in the box, the trees from which the branches had been cut 

 were examined and found to contain nothing but larvae. Some more 

 branches were cut on this date and placed in a tin can, where they 

 were kept moist. The first beetles emerged from these on August 

 24, or more than thirty da} 7 s after adults had emerged from the dry 

 branch. On August 30 many adults had emerged. September 20 

 ten living adults and many dead ones were taken from the can, and on 

 October 2 several more dead ones were removed. 



When the trees were examined on July 20, a larva was found min- 

 ing in a two-year-old branch less than one-half inch in diameter, and 

 the cocoon of a parasite of the borer was found in one of the mines, 

 but the adult parasite was not reared. Many dead borers were found 

 in their mines in the trunks and branches surrounded by a white 

 powdeiy fungus. 



The trees were again examined on September 1-1, when adults were 

 found abundant on the foliage, branches, and stems, and also on 

 flowers of golden-rod. Adults and pupae were also found in con- 

 siderable numbers in the dead wood of broken branches, as well as in 

 the living wood, and dead larvae were frequent. Larvae of an elaterid 

 (click beetle) were quite frequent in the wood, where they had evidently 

 been feeding on the locust borer. 



Examination during August, 1905, of the locust on a hill near 

 Kanawha Station, W. Va., where this tree forms the principal growth 

 over old abandoned fields and in the adjacent forests, showed that the 



