THE LEAD-CABLE BORER IN CALIFORlSriA. 



21 



No. 1 (commercially pure lead) were also penetrated, 

 sheathinff is over one-sixteenth inch in thickness. 



The lead 



RESULTS OF EXPERIMENTS AT FALLS CHURCH, VA., 1918 AND 1919. 



It is believed that the results obtained at Falls Church, Va., laere 

 not conclusive and that climatic conditions may be an important 

 factor influencing attack by the beetles. The No. 4 lead, with a higher 

 per cent of tin in the alloy (97 per cent lead + 3 per cent tin), was 

 not attacked. The sheets of lead No. 5 (commercially pure), with 

 emer}^ embedded, were not large enough to wrap about the logs. 

 Antimony is apparently of no value in resisting the attack of the 

 beetles. 



It was decided that this test should be continued in California and 

 that no further infested wood should be shipped to the East. Of 



^4 



♦.♦'< 



W 



^/-• 







Fig. 15. — Interior of experimental cage at Falls Church, \n., showing lead-sheathed cables 

 of different alloy composition suspended on different types of rings from beams of roof. 



course, this is not an absolutely fair test, since it is well known that 

 emerging insects will, if necessarj^, penetrate materials which they 

 would not ordinarily attack. 



Lead embedded with emery has a disadvantage in that it will rust, 

 will " run," and would discolor whatever it fell on beneath the aerial 

 cable. 



TESTS AT LOS GATOS, CALIF., 1918-1920. 



Emergence Experiments. 

 To determine just what the beetle is able to do and, if possible, to 

 find a repellent or nonpenetrable substance for a cable sheath, a 



