A BATTLE WITH BEETLES. 



275 



12 tunnels to one superficial foot of bark, and in some instances 

 as many as 20 to 24 to one foot. 



By the first week of May I found the whole of the trap trees fully 

 occupied, and during that week I cut down a fresh lot of trees for 

 traps. On the eighth day thereafter, beetles began to occupy them. 

 Again, in the first week of June, I cut down a few more trees for 

 traps, and on the seventh day beetles began to occupy them. 

 The tunnels were less numerous in the trees cut down in May 

 than in those cut down in March ; and in those cut down in the 

 beginning of June, the tunnels were but thinly scattered over the 

 lower part of the tree. 



On the first of July I began the work of destroying the broods, 

 by stripping the bark from the trunks with old spades. The 

 trees were collected into suitable centres and barked, this being 

 a very easy process, as the larvse had eaten the whole of the 

 inner liber, and thus detached the bark from the stem. 



Two men collected and stripped about twenty-eight trees per 

 day, each tree containing on an average about ten thousand 

 larvse and beetles, young and old. In all, about five hundred 

 stems were used as trap trees, and by means of these not less 

 than five millions of beetles must have been destroyed during the 

 summer of 1898. 



Again, by the middle of March 1899, the fir woods were 

 provided with trap trees, and by the middle of April they were 

 largely occupied by pairs of beetles. During the season about 

 two hundred trees were used as beetle traps ; all these were fully 

 occupied, and were then treated as in the summer of 1898. A 

 new enemy to the beetles I found in many of their breeding- 

 tunnels, viz., Rhizophagus depressus. This is a small insect about 

 the same length as the beetle, but very narrow and thin, and of 

 a dark colour. In the tunnels in which I found this insect, the 

 eggs of the Pine Beetles had disappeared, and it soon became 

 evident to me that Rhizophagus had devoured them. In some 

 of the woods, so numerous wei'e the "egg eaters" that nearly 

 one-half of the tunnels failed to hatch out a single grub. 



A second enemy of our pest also appeared in the form of the 

 Large Spotted Woodpecker, which is rarely seen in Aberdeenshire. 

 These birds appeared in twos and threes during the autumn of 

 1897, and disappeared again in the spring of 1899. They fed on 

 the grubs of weevils and beetles, and by tapping on the bark 

 could locate the exact spot where the grub was hidden. 



