U. S. D. A., B. E, Bui. 58. Part HI. p, . t ,. , , . _^^ 



r. 1. I., March 5, 1907. 



SOME INSECTS INJURIOUS TO FORESTS. 



ADDITIONAL DATA ON THE LOCUST BORER, 



{Cyllene robini!e Forst. )« 



By A. B. Hopkins, 

 In Charge of Forest Insect Investigations. 



This part of Bulletin 68 contains a partial revision of Part I, with 

 additional information based on the results of subsequent investiga- 

 tions by the writer and one of his assistants, Mr. W. F. Fiske. 



SEASONAL HISTORY. 



The data under this head refer to the District of Columbia and vicin- 

 ity, latitude 39°, altitude 10 to 90 feet above tide. 



HIBERNATION. 



Hibernation begins soon after the larvfe hatch from eggs deposited 

 at various times from August to October, and the period is passed as 

 minute larvae, scarcely longer than the eggs from which they hatch, in 

 small individual hibernating cells excavated b}- them just beneath the 

 corky bark and in the outer layers of the living bark on the main 

 trunk of the larger to small trees or small saplings, and larger to small 

 branches. 



ACTTVITY OF THE OVERWINTERED LARVJE. 



Activity of the overwintered larvae begins in April, or with the begin- 

 ning of the movement of the sap in the bark and just before the leaf 

 buds open. In 1906 activity began April 11; on April 13 the more 

 advanced individuals had entered to the wood, on the 16th were groov- 

 ing the surface, and on the 25th some of them had entered the wood. 

 By May 11 nearly all of them had entered the sapwood and some of 

 them had extended their burrows into the heartwood and were rapidly 



o Order Coleoptera, family Cerambycidae. 



31 



