THE LEAD-CABLE BOREK IN CALIFORNIA. 23 



the season, and others were confined in lamp-chimney cages with 

 freshly emerged beetles. 



Cahle Experiments. 



Besides the experiments with the insects and the wood, a number 

 of experiments were conducted with the insects and the regular tele- 

 phone cables (PL X, Figs. 1-4) to see if any facts could be discov- 

 ered that would throw light on the reason for the attacks and the 

 methods of preventing them. 



Caged cable. — Two large screened cages were built out of doors 

 !'cnd a number of cables were suspended in these in as normal a man- 

 ner as possible. Different types of suspension rings were used and 

 some cables were charged Avith a 60-cycle lighting current of elec- 

 tricity, while others were left uncharged. Numerous freshly- emerged 

 beetles were placed in the cages, some unconfined and some confined 

 in smaller cages built around a short length of cable and one or two 

 suspension rings. (PL X, Figs. 2 and 4.) Some sections of the 

 cable were treated with substances to make it more or less attractive 

 or to trap the insects. These substances were oak-bark tea, tallow, 

 refined paraffin, P. & B. paint, and pine tar. 



Service cable. — To be sure that the actual conditions met with in 

 the commercial cables were present in the experiments, several small 

 cages were placed around the service cables of the Los Gatos Tele- 

 phone Co. (PL X, Fig. 1.) These were kept supplied with beetles 

 and the results noted. Some of the cages inclosed suspension rings 

 and others were attached between the rings close enough to the lead 

 to allow the beetles leverage for boring at any point along the cable. 



Several tests were made on the commercial cables to see if any 

 magnetic fields existed about them, but no evidence was found that 

 any existed. Several times beetles were placed in a magnetic field 

 created by an ordinary magnet, but so far as could be determined 

 this had no effect on them, 



results op expekiments at los gatos, calif., 1918-1920. 



Emergence Experiments. 



As the emergence experiments were numerous, the results can best 

 be given in a series of tables (Tables 1-4) and photographs (Pis. 

 IV-IX). None of the metals, repellents, or poisons used appeared ef- 

 fective against normal emergence except the zinc (Table 2), (PL 

 VI, Fig. 4), steel (Table 2) (PL IV, Figs. 1-3), and possibly friction 

 tape (Table 2). The beef tallow when softened by the sun stopped 

 the emergence (Table 4) (PL IX, Fig. 1). As at Falls Church, Va., 

 beetles entered 30-millimeter corks used as stoppers to -vdals contain- 

 ing alcohol. (PL IX, Fig. 4.) 



