10 



BULLETIN 1107, U. S. DEPARTMENT OF AGRICULTUEE, 



are through with a sec- • 

 tion of wood, nothing 

 remains but the bark 

 and enough solid wood 

 to hold the mines to- 

 gether. All of the rest 

 is reduced to numerous 

 holes (the egg galleries 

 and exit holes) and the 

 winding larval mines 

 closely packed with the 

 meal-like boring dust. 

 (Figs. 7 and 8.) 



In special cases the 

 beetles may attack and 

 kill living trees. On 

 September 28, 1919, 

 Mr. Hartman found a 

 cherry tree {Prunivs 

 avium) in Los Gatos, 

 Calif., with the foliage 

 fading. Close exami- 

 nation showed numer- 

 ous small holes in the 

 bark at the bases of the 

 branches and buds and 

 in rough spots on the 

 bark of the trunk. 

 Some of these holes 

 contained Scobicia 

 beetles and many of 

 them were the en^ 

 trances to galleries 

 which encircled the 

 branch or trunk just 

 beneath the surface of 

 the outer wood. No 

 other cause for the dy- 

 ing of the tree could be 

 discovered. No eggs 

 or larvse were found. 

 In the laboratory at 

 Los Gatos, numerous 

 beetles which emerged from the wood stored for rearing purposes 

 entered a cedar cigar box containing large vials of alcoholic speci- 



al,-. 7. — Work Oif the California lead-cable borer in Cali- 

 fornia live oak (Quercus agrifolia), Los Gatos, Calif. 

 Note that the wood is " powder-posted." The larger 

 holes were made by a roundheaded borer. Natural size. 



