8 BULLETIN 1107, U. S. DEPARTMENT OF AGRICULTURE. , 



Statistical records have not been kept until recently. The Cali- 

 fornia experience of recent years can be seen from the map. (Fig. 5.) 



Cable trouble due to insect boring seems to approach most closely 

 to regularity of occurrence in California, where the districts affected 

 extend along the coast from San Diego to some distance north of 

 San Francisco, although trouble has been reported at points as far 

 inland as Sacramento and Marysville. 



The extent of the beetle injury to the lead cables appears to vary 

 considerably during different years. In 1913 it was particularly bad 

 at Marysville, in 1917 at Monterey and Salinas, and in 1918 at Wat- 

 sonville. Part of this variation may be due to the fact that tallow 

 has been used on some cables. There have been no cases of attack 

 found at points protected by tallow, but the experience has not been 

 long enough to indicate whether this freedom from attack is acci- 

 dental and due to the absence of beetle attack for the years during 

 which the tallow has been under trial or is actually due to its turn- 

 ing the insect away. 



It should be noted that occasionally many holes are found in the 

 same piece of cable and are necessarily taken care of in clearing the 

 one case of trouble. The number of holes may vary from 1 to a span 

 (section of cable between two poles, the distance averaging 100 feet) 

 to 125 to a span. In 1913, 106 holes occurred in one span at Marys- 

 ville; in 1917, 44 occurred under 44 consecutive rings in one span 

 and 30 under 30 consecutive rings in the following span at Monterey ; 

 and in the same year 125 holes occurred in one span at Salinas. As 

 one hole may put from 50 to 600 or more telephones out of use for 

 from 1 to 10 days, the damage is rather extensive. 



Cases of cable trouble are also occasionally reported where insects, 

 in making their way out of a wooden pole, strike cable laterals or 

 risers and cut into the sheath. One such case was reported from 

 Kingston, N. Y., in the fall of 1918 and another from Orlando, Fla., 

 in July, 1919. In the latter case cable trouble occurred from wetting 

 by a shower before the beetle had cut its way out and it was caught 

 and identified as Eburia distincta Hald. Such experiences as these 

 demonstrate that many wood-boring insects are able to cut cable 

 sheath. (Fig. 6.) 



The following are additional records reported to the Bureau of 

 Entomology : 



A case of insect damage (bostrichid) to cable occurred at Savan- 

 nah, Ga., in 1915; another at Galveston, Tex., in 1920, caused by 

 Xylobiops sp., probably basilar e Say. 



Among the cases where the identity of the insect causing the injury 

 is in doubt is a report to Dr. F. H. Chittenden, of the Bureau of 

 Entomology, in November, 1906, of small punctures in the lead cov- 

 ering of cables at Watsonville. Calif. These were thought to have 



