THE LEAD-CABLE BORER IX CALIFORNIA. 31 



town of Los Gatos, at Palo Alto, and at Santa Barbara. The work 

 was carried on in cooperation with the American Telephone & Tele- 

 graph Co.. the Pacific Telephone & Telegraph Co., the Santa Bar- 

 bara Telephone Co., and the Los Gatos Telephone Co. A total of 

 6,953 beetles were reared and used in the various experiments. One 

 of the most interesting results obtained was the determination that 

 the beetles are unable to penetrate pure gum rubber. Another is the 

 catching of the beetles by placing sticky tree-banding material on the 



cables. ~ ^ 



Cage Expeeiments. 



To determine if possible the attractive effect of varying currents 

 of electricity on the beetles the following experiments were con- 

 ducted. 14 



Experimental cage. — One of the large cages used in 1920, which 

 contained seven cables 10 feet long suspended from the messenger 

 strands by rings of various types, was again used. An engineer of 

 the Pacific Telephone & Telegraph Co. designed an apparatus which 

 made it possible to use the alternating currents of higher talking 

 frequencies as well as the currents of lower commercial frequencies 

 used in 1920. The idea was to create in these test cables any condition 

 that could occur in the regular commercial cables. 



Of the seven cables in the cage, four were connected with the ap- 

 paratus and three were left " dead." Cable No. 1 had four pairs 

 in parallel tapped to a 1,000-cycle circuit and the far ends shorted; 

 cable Xo. 2 had four pairs in parallel tapped to a 1,000-cycle circuit 

 and the far ends open ; cable Xo. 3 had four pairs in parallel tapped 

 to a 1,000-cycle circuit and the far ends shorted and connected to 

 the sheath; cable Xo. 4 had the sheath connected to the 1,000-cycle 

 circuit. Two drops were used, No. 1 for cables 1, 3, and 4, and No. 

 2 for cable 2. Both drops could be used singly or together and a 

 battery could be switched in or out. 



Some beetles were liberated in the main cage and were free to 

 attack any of the cables, charged or dead, while others were confined 

 in smaller cages to the various cables. During the season of five 

 months, April 22 to September 27, 2.714 beetles were liberated in 

 the cage on 24 different occasions of varying climatic conditions. A 

 few slight borings were noted on cables 2 and 3, but as a whole the 

 experiment was without any definite positive result. 



Aerial cage. — Two small wire-screen cages were placed around a 

 regular 25-pair commercial cable in Palo Alto. These cages were 

 placed on the cable where it ran through the top of a large acacia 

 tree, which caused varying conditions of light and shade. Each 

 cage inclosed several suspension rings as well as a section of the cable. 



14 All of the officials of the Pacific Telephone & Telegraph Co., the Santa Barbara 

 Telephone Co., and the Los Gatos Telephone Co. cooperated to the fullest extent in the 

 experiments. 



