August, '21 1 burke: carpenter worm control 369 



It is believed that these instances of damage to timber by phytopha- 

 gous but non-wood-boring Lepidopterous larvae are imusual and of 

 especial interest ; however, such damage is of only occasional occvtrrence 

 and more or less accidental. Nevertheless, the damage to the railway 

 car in California and the building in Virginia is of no little economic 

 importance. Of particiilar interest is the instance of damage to creo- 

 soted wood. 



NOTES ON THE CARPENTER WORM (Prionoxystus robiniae 

 Peck) AND A NEW METHOD OF CONTROL 



By H. E. Burke, Specialist in Forest Entomology, Forest Insect Investigations, Bu- 

 reau of Entomology, U. S. Department oj Agriculture 



One of the worst pests of the native live oak (Quercus agrifolia) and the 

 introduced elms {Ulmus campestris and varieties) in California is the 

 carpenter worm. The tnmks of many of the finest street and yard 

 trees are riddled by its large winding mines. The dirty brownish bor- 

 ings cover the bark and the ground at the bases of the trees and the 

 entire trunk takes on a very disagreeable appearance. As the work 

 continues year after year and the tree tries to heal over the wounds, 

 the bark becomes roughened and unhealthy looking and the tree ap- 

 parently is more susceptible to new attacks. Fortunately most of 

 the mining is done in the wood and for a nimiber of years the health of 

 the tree appears to be little affected. In the worst cases, however, 

 the tree is unable to overcome the repeated attacks and dies. 



The writer has seen live oaks killed by this species at Palo Alto and 

 Santa Barbara and elms in San Jose. There are some heavily infested 

 trees at Los Gatos. Mr. R. D. Hartman observed the work to be com- 

 mon in the live oak in the Niles canyon in Alameda County and Mr. 

 CM. Packard reports elms badly infested in Sacramento. 



Besides the live oak and the ekn, the California hosts of the carpen- 

 ter worm observed by the writer are the white oak (Q. lobata), the 

 willow (Salix lasiolepis) and probably the cottonwood {Populus trtcho- 

 carpa) . We have not found it in the black locust {Rohinia) which was 

 the original host reported in the Eastern states. An attempted in- 

 troduction in the blue oak {Q. douglasn) failed. Childs (Month. Bui. 

 Calif. State Com. Hort., Vol. Ill, p. 264) gives locust and carob as 

 additional hosts. 



