THE PINE INVESTIGATION. 381 



primary attack, those making a secondary attack and those 

 which are dependent upon other species to make an entrance in 

 the bark, and otherwise produce favorable conditions for the 

 development of their broods. 



THE MINES OR GALLERIES. 



The Scolytids differ in their breeding habits from nearly all 

 of the other bark and wood infesting insects, in the fact that 

 the adults bore directly into the bark or wood and form mines or 

 galleries in which their eggs are deposited. Each species or 

 group of nearly related species, as a genus, not only have a 

 characteristic method of attack, but excavate their galleries ac- 

 cording to some more or less uniform plan, or pattern, by which 

 alone the species or genus may often be determined. 



The different parts of these galleries, excavated by the parent 

 beetles and their young or larvae, are designated by the fol- 

 lowing nomenclature: 



The main entrance is the first entrance made by the parent 

 beetle in the bark or wood. Those excavated by the bark bee- 

 tle extends to the inner bark or surface of the sapwood 

 where they open into the 

 nuptial chamber, or branch 

 off' into one or more galler- 

 ies. Those excavated by am- 

 brosia beetles extend direct- 

 ly through the bark and into 

 the wood. 



Side entrances and exits 

 are passages extending from 

 the primary gallery to the 

 surface of the bark. 



The nuptial chamber. 

 This is a large space at the 



innpr pnrl nf thp main pn Fi - LIII. Nuptial chambers of Tomi- 



' cus cacographus in pine. 



trance, to the galleries of so- 

 cial species of both bark and timber beetles, which is utilized 

 as a kind of reception chamber for the sexes, and as a central 

 court from which the primary galleries extend. 



