142 
THE SCOLYTID BEETLES. 
ECONOMIC FEATURES. 
, It is said that this species prefers to attack the bark on the base of 
the trunks and roots of sound or healthy trees, and that the connect- 
ing of the broad larval chambers from the same egg gallery or from 
several galleries has the effect of girdling the tree, either causing its 
death or a weakened condition which attracts other barkbeetles to 
complete the destruction. Young as well as old trees are attacked, 
but, while this species will breed in standing injured or weakened 
trees, it rarely breeds in felled ones. It apparently prefers the 
spruces, but will, according to dif- 
ferent authors, attack pine, fir, 
and larch. 
The evidences of attack are 
masses of gum or resin and so- 
called pitch tubes, mixed with 
reddish boring dust. 
METHODS OF CONTROL. 
Removing the bark from the in- 
fested trunk and roots, or scorch- 
ing it if not removed, is recom- 
mended to kill the broods. Coat- 
ing the trunks of the trees with 
a preparation of tobacco water, 
Spanish blood, lime, fresh cow 
dung, etc., is recommended as a 
preventive. 
After the above was written 
the writer received a paper on the 
genus Dendroctonus from Dr. G. 
Severin (1908), director of the 
Royal Museum of Natural History 
of Belgium. A large series of 
specimens of the beetle and its 
work was also received from Doctor Severin, which was of special 
value and interest. Doctor Severin's paper covers the more impor- 
tant historic and economic information on the species recorded in 
European literature to 1908. Some of the information in the paper 
that is of special interest in connection with a discussion of all of 
the species is summarized as follows: 
Fig. 92. — The European spruce beetle (Den- 
droctonus micans): Adult. Greatly enlarged. 
( Author's illustration.) 
Information from Paper on the Genus Dendroctonus, 
(1908,, pp. 1-20). 
by Dr. G. Severin 
Dendroctonus micans alone, of all the hylesinids, and perhaps of all the scolytids, 
appears to love the resin and to live there with ease. It neglects the weak trees and 
is found principally upon trees full of vigor, of an age of 30 years and more, where it 
