THE LEAD-CABLE BORER IN CALIFORNIA, 6 



Another ptinid beetle, Mezimn americanwm Lap., also damages 

 gilded chandeliers, according to Dr. E. A. Schwarz, of the Bureau of 

 Entomology. 



A type of injury which occurs fairly commonly is that caused by 

 larder beetles (species of Dermestes) to lead telephone fuses. 



The most common, extensive, and serious injury to metal by in- 

 sects, however, is that caused to the lead sheathing of aerial cables; 

 such damage occurs throughout the world and is caused by a great 

 variety of insects {30)^ but the most prevalent and serious injury 

 is that caused by bostrichid beetles. 



INJURY TO LEAD FUSES BY INSECTS. 



The purpose of the tubular lead telephone fuse is to protect the 

 telephone equipment from heavy currents ; the action of the fuse is to 

 melt or "blow," thus "grounding" the objectionably heavy current 



Fig. 1. — The "hide beetle" {Dermestes vulpinus) : Adult, 

 enlarged 4 times ; at left, mandible, enlarged 20 times. 



Fig. 2.- 



-Typical dermestid larva (larva of Dermestes nidum avium). 

 Greatly enlarged. (After A. Boving.) 



and preventing further damage. These fuses are made from paper 

 or fiber treated with zinc chlorid and hardened by subjection to con- 

 siderable pressure. The wire or tape used in these fuses is chiefly 

 lead, although hardened with the addition of a small percentage of 

 another hardening metal such as tin or antimony. Suitable termi- 

 nals are provided at the ends of the tube for terminating the fusible 

 conductor. By eating through the lead the insects make it necessary 

 to replace the fuse just as if it had been operated in its regular 



