SOME INSECTS INJURIOUS TO FORESTS. 



Bureau of Entomology unci the Forest Service in the investigation of 

 insect enemies of the black locust was proposed and adopted, b}' which 

 the subject is receiving special attention from the viewpoint of both 

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

 results. 



CHARACTER, OF THE INSECT AND ITS WORK. 



The locust ])orer is a whitish, elongate, so-called ' ' round-headed " grub 

 or larva (tig. 1), which hatches from an ego; (tig. 2) deposited by a black 

 or brown and mellow striped long-horned winged l)eetle (fig. 3) found 

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

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

 trees from August to 

 O c t o b e r, and the 

 young borers (fig. 2, 

 /-*, r) hatching there- 

 from mine into the 

 outer portion of the 

 living inner l)ark (tig. 

 5), where they pass the 

 winter, and in the 

 spring bore through 

 the bark into the sap- 

 wood and heartwood. 

 Here thev transform 

 in July and August to 

 pupie (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 (PL 1) consists 

 of Avounds in the bark and .siipwood wiiich. if sufficiently severe or 

 repeated year after 3'ear, result in either a stunted worthless growth 

 or the death of 3"oung and old trees, while the numerous worm holes 

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



The pi-esence of the insect in injurious numbers is indicated (L) 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 larvie are at work in the bark, 

 during April and ]\Iay; (3) by the whitish sawdust ])orings lodged in 



Fig. 1.— The locust borer (Ci.illcne robinur): a, larva, dorsal view; b, 

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

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



