INSECT DAMAGE TO TELEPHONE AND TELEGEAPH POLES. 3 



usually sound. Even if tJie damage is not serious enough to cause 

 the poles to break off uncKn- strain, tlie}' are likely to go down during 

 any st(jrni, and tlius put the wire service out of commission; such 

 damaged poles are a serious menace along tlie right of way of rail- 

 roads. Poles that appear sound on the exterior may have the 

 entire basal interior riddled, and the damage is not noticed until the 

 poles break off. If merely isolated poles are injured so as to cause 

 them to break off, they simply lean over, but if several adjacent poles 

 are affected, especially where there is any unusual strain, that por- 

 tion of tlie line is very likely to go down. 



THE PRINCIPAL INJURIOUS SPECIES. 



The principal injurious species is the chestnut telephone-pole 

 borer, or pole borer,^ which is an elongate, creamy-white, wrinkled, 



Fig. 2.—?, The pole borer: Male and female bjetles. ,', The pole borer: Young 

 larva'. /, Slightly enlarged; ?, twice natural size. (Author's illustration.) 



round-headed grub or larva (fig. 2, 2). It hatches from an egg depos- 

 ited by an elongate, mahogany -brown, shiny, flattened, winged 

 beetle, from two-fifths to four-fiftlis of an incli in length (fig. 2, 1). 

 It appears that tlie eggs are de])osited from August to October in 

 tlie outer layers of tlie wood of tlie ])()le near the surface of the 

 ground. The young borers, upon hatching, excavate shallow gal- 

 leries in tlie sapwood, then enter tlie heartwood, tlie mines being 

 gradually enlarged as they develop. As they proceed they closely 

 pack the fine boring dust behind them. This peculiar semidigested 

 boring dust, wliicli is characteristic of their work, is redtlish to dun- 



' Parandra brunnca Fab. Since the publication of Bulletin 94, Part T, of thi.s Bureau, this borer, first 

 found to be injtiriou.s to chestnut telephone poles, has been found injurious (o arborvitne poles, and as it 

 also injures telegraph poles, the name "pole borer" is more appropriate and comprehensive. 



