94 
THE SCOLYTID BEETLES. 
and adults in individual cells at the farther end or toward the 
middle of their larval mines, which are exposed in the inner bark 
when it is removed from the tree. Both the egg galleries and larval 
mines cause marks and grooves on the surface of the wood. After 
the new broods of adults become matured, they burrow through the 
intervening bark between their cells, and congregate in the general 
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Fig. 54.— The Black Hills beetle: Galleries in bark and marked on scoring chip. About one-third 
natural size. (Author's illustration.) 
cavity thus formed, until the proper time for them to emerge, when 
they all come out and fly in swarms to attack the remaining living 
timber. 
Sufficient information relating to the flight of this species has 
been secured to indicate quite conclusively that it flies in swarms 
during the day, and probably at night. 
