THE PINE INVESTIGATION. 327 



of the destructive pine bark beetle ( Dendroctonus frontalis}^ 

 while encouraging in indicating the possibility of the trouble 

 coming to an end, was at first discourging so far as the success of 

 the experiment was concerned, since the habits of this bark bee- 

 tle correspond more nearly to that of the bark beetles upon which 

 the Clerids fed in Europe, and would thus have offered better 

 conditions for its multiplication than any other of our native 

 bark beetles. It was found, however, that both in the pine 

 and the spruce, living examples of many other species of bark 

 beetles occurred in enormous numbers in the bark of injured, 

 dying and felled trees, and although none of these offered the 

 best conditions for the attack of the Clerid, it was thought that 

 with proper precautions, it would attack them and become es- 

 tablished in the localities in which colonies were placed. Where 

 trees were found that died last fall, as well as those which were 

 then dying from previous injuries by the destructive species, 

 fairly good conditions were found for the Clerid to survive, as 

 also in the bark of recently felled trees. Therefore, where 

 such conditions were found near or in the best tracts of living 

 timber, a tree or log was selected which had coarse flaky bark 

 in which the pupae and larvae could be secreted, and a colony 

 of from 25 to 100 were placed on it. When the desirable con* 

 ditions were not found, one or more trees were felled and oth- 

 ers girdled so as to attract the bark beetles to them. The im- 

 ported insects were then placed in the moss or loose bark at the 

 base of the girdled trees, or on the trunks of the felled ones. 



If colonies were placed some distance from where the timber 

 was being felled for logs, instructions were given to girdle or fell 

 some more trees in the same locality in August and the follow- 

 ing spring, in order to provide a constant supply of bark beetles 

 which would thus be attracted to them. Careful and detailed 

 instructions were given to a responsible representative of each 

 of the companies with reference to subsequent location of col- 

 onies from the specimens which would be forwarded to them 

 from time to time, as received from Germany. 



During the fall of 1893, adults that came in the packages, 

 and as many as could be brscl from pupa were placed together 



