THE GENUS DENDROCTONUS. 



157 



las fir, and it is not likely that it will infest these trees, but it has been 

 found in the eastern larch. 



It is often exceedingly abundant in the stumps of felled trees 

 where timber-cutting operations are carried on, in fire-scorched trees, 

 and especially in the bark at the base of those kOled by other species 

 of Dendroctonus, or by lightning, or storm, or otherwise injured and 

 broken. It shows a decided preference for the bark on the base of 



Fig. 99.— The red turpentine beetle. Work in bark at.base of tree: a, Entrance and pitch tube; b, egg 

 gallery: e, boring dust an^ resin: d, pupal cell; e, pupa: /, larvse at work feeding on inner living 

 bark; g, exit burrows; k, resulting old scar or basal wound, often referred to as basal fire wound; 

 i, inner bark with outer.corky bark removed. (Author's illustration.) 



pine trees and stumps, and is rarely common in the logs or prostrate 

 trunks, even of pine. 



The parent beetles excavate their broad, irregular, sometimes 

 branched, longitudinal egg galleries, from a few inches to many feet in 

 length, through the inner living bark. If the bark is living and 

 healthy and fuU of resin, the progress in making an entrance through 

 the inner bark and extending the galleries is slow, and often large 

 masses of resin or so-called pitch are pushed out at the entrance before 



