2 SOME INSECTS INJURIOUS TO FORESTS. 



Bureau of Entomology and the Forest Service in the^ investigation of 

 insect. enemies of the black locust was proposed and adopted, by which 

 the subject is receiving special attention from the viewpoint of both 

 the forester and the entomologist, with the primary object of practical 

 results. 



CHABACTEB Or THE INSECT AND ITS WORK. 

 The locust borer is a whitish, elongate, so-called ' ' round-headed " grub 

 or larva (fig. 1), which hatches from an egg (fig. 2) deposited by a black 

 or brown and yellow striped long-horned winged beetle (fig. 3) found 

 on the trees and on the flowers of golden-rod from August to October. 

 The eggs are deposited in the crevices of the bark of living, growing 



trees from August to 

 October, and the 

 young borers (fig. 2, 

 h, c) hatching there- 

 from mine into the 

 outer portion of the 

 living inner bark (fig. 

 5), where they pass the 

 winter, and in the 

 spring bore through 

 the bark into the sap- 

 wood and heartwood. 

 Here thej'^ transform 

 in Julj' and August to 

 pupae (fig. 4) and in 

 August and Septem- 

 ber to adult beetles, 

 which soon emerge 

 from the trees and de- 

 posit eggs for the next 

 annual generation of 

 borers and beetles. 



The injury to the 

 trees (PI. I) consists 

 of wounds in the bark and sapwood which, if sufficiently severe or 

 repeated year after year, result in either a stunted worthless growth 

 or the death of young and old trees, while the numerous worm holes 

 in the wood reduce its commercial value or render it worthless. 



The presence of the insect in injurious numbers is indicated (1) by 

 the frequency of the adults on the golden-rod flowers and on the treeS, 

 from August to October; (2) by the slight flow of sap and by the 

 brownish borings where the young larvse are at work in the bark, 

 during April and May; (3) by the whitish sawdust borings lodged in 



Fig. 1.— The locust borer ( C?/H«ne robinise); a, larva, dorsal view; 6, 

 same, lateral view. Line at rightrepresents natural length (origi- 

 nal). The larva in profile should show minute prothoracic feet. 



