THE PINE INVESTIGATION. 



397 



segment. Described from alcohol specimens and drawings 

 from life. 1 



THE GALLERIES. 



Preliminary galleries These are usually in the form of 

 short curved excavations made by the beetle in the living or 

 healthy bark, which are either abandoned before completion, 

 further excavation is checked by the death of the beetle. They 

 are easily distinguished Iroin brood galleries by the fact that 



Fig. LXI. Preliminary and brood galleries of Dendroctonus frontalis. 



they are packed with borings and hardened pitch gum, attended 

 in living and partially dead bark, by discolorations in both the 

 bark and wood; also by the absence of egg cavities or larval 

 mines. In dead trees, the bark and wood adjoining the prelim- 

 inary galleries is the last to decay. One or more inches of the 

 entrance end of a brood gallery when presenting this condition 

 may be termed preliminary galleries. 



The main entrance is located in the crevices or cracks in 

 the outer bark, and if it is an entrance to a preliminary gallery 

 takes an upward or a lateral course through the inner or liv- 

 ing bark, often extending for some distance through the outer 

 portion of the living bark before the inner layer is penetrated. 

 If it is an entrance to a brood gallery, which has been excavat- 

 ed after the vitality of the tree had been weakened and when 

 there was little flow of turpentine, it extends directly through 

 the bark to the outer layer of the wood. The entrance to the 



1. The failure to take descriptive notes of the larvae and pupae when living mate rial 

 pould be had, makes their descriptions incomplete. 



