Bui. 1107, U. S. Dept. of Agriculture. 



PLATE VI 



Fig. 1. — Section of lead showing the branched minings and 

 mandibular impressions of two beetles. This was the 

 underside of the second layer of lead, which was rolled 

 unevenly and permitted the light to penetrate; thus the 

 minings were irregular. Enlarged If times. (Table 2, 

 No. 4.) Photograph by R. D. Hartman. 



Fig. 2.— First layer of tin-coated lead down after being 

 removed from infested section, showing 58 attempts, i 

 of which 24 were successful, in penetrating at least i 

 the first thickness . In many cases where the beetles . 

 attempted to escape between the section and the 

 lead, they mined more in the lead than those that 

 penetrated several thicknesses. One-fourth natural 

 size. (Table 2, No. 52.) Photograph by R. D. 

 Hartman. 



Fig. 3.— Typical beetle mine or single exit burrow 

 in lead sheathing, enlarged 6^ times. Beetle had 

 mined about two-thirds through the sheathing. 

 Photograph by R. D. Hartman. 



Fig. 4.— First layer of sheet zinc after being removed from 

 infested section, showing 31 attempts, of which 2 were 

 successful, in penetrating one thickness. These are desig- 

 nated by arrows. Three-tenths natural size. (Table 2.) 

 Photograph by R. D. Hartman. 



THE LEAD-CABLE BORER. 



