384 YEARBOOK OF THE DEPARTMENT OF AGRICULTURE. 



which the broods develop together in the main burrows (figs. 43 and 

 44), the other in which the individuals develop in short separate side 



FIG. 44. Work of ambrosia beetle, Xyleborus ccteus, in hickory wood: a, larva, 6, pupa; c, adult ' 

 beetle, natural size; d, character of work in lumber cut from injured log; e, bark; /, sapwood; 

 </, heartwood. (Original.) 



chambers extending at right angles from the primary gallery (fig. 45). 

 The galleries of the latter type are usually accompanied by a distinct 

 staining of the wood, while those of the former are not. 



FIG. 45. Work of ambrosia beetles in oak: a, Monarthrum mali and work; b, Platypus com} 

 and work; c, bark; d, sapwood; e, heartwood; /, character of work in lumber from injured 

 (Original.) 



The beetles responsible for this work are cylindrical in form, apj 

 ently with a head (the prothorax) half as long as the remainder of 



