4 INSECT DAMAGE TO TELEPHONE AND TELEGRAPH POLES. 



nish yellow in color and has a claylike consistency. The burrows 

 eventually end in a broad chamber, the entrance to which is plugged 

 with excelsiorlike fibers of wood. Here is formed the resting stage, 

 or pupa, which transforms to the adult beetle. Often all stages, from 

 very young grubs only about one-fourth inch long to full-grown 

 grubs over 1 inch long, pupge, and adults in all stages to maturity 

 are present in the same pole. Adults have been found flying from 

 July to September. 



The insect attacks poles that are perfectly sound, ])ut will work 

 where the wood is decayed; it will not, however, work in wood that 

 is "sobby" (wet rot), or in very "doty" (punky) wood. It has not 

 yet been determined just how soon the borers enter the poles after 

 they have been set in the ground. However, pedes tliat had been 



Fig. 3.— Damage to an untreated chestnut telegraph pole near surface of ground 

 by the pole borer. (Author's illustration.) 



.♦. 



standing only four or five years contained larvae and adults of this 

 borer in the heartwood, and poles that had been set in the ground 

 for only two years contained young larvse in the outer layers of the 

 wood. 



The presence of the borers in injurious numbers can be deter- 

 mined only by removing the earth from about the base of the pole; 

 the large holes made when the adults come out are found near the 

 line of contact with the soil. Often large, coarse borings of wood 

 fiber project from these exit holes. Sometimes the old dead parent 

 adults are foimd on the exterior of the poles underground. During 

 August the young adults may be found in shallow depressions on the 

 exterior of poles below the groTmd surface. 



