108 



FOREST ENTOMOLOGY. 



Hylurgus piniperda (Linn.) 



This beetle is very destructive to the young shoots of Scots pine, 

 and has an interesting life-history. During the winter months many 

 of the perfect insects hibernate in rough bark, or otherwise bore a 

 hole in the bark of healthy standing trees, just enough for covering, 

 but this winter burrow is in no way injurious to the standing tree. 

 The burrows, however, on the stem of the tree may be best seen 



Fig. 101. Shoot of Scots pine, showing the 

 entrance-hole, and a slice removed to 

 show the boring of a pine beetle. (From 

 ' The Forester,' by J. Nisbet.) 





'ig. 102. Showing mother and larval 

 galleries in process of formation. (From 

 'The Forester,' by J. Nisbet.) 



months after the exit of the beetle. The exit-holes are clean-cut 

 openings, surrounded by a fringe of hard resin, which has in conse- 

 quence issued from the bottom of the excavation, as the boring has 

 been sufficiently deep to reach the vital bast. A few of the beetles 

 hibernate in the shoots, which fall with the buried insect in autumn 

 (fig. 101). In early April or the end of March they withdraw from 

 their winter-quarters and commence their breeding operations. The 

 female beetle either selects a sickly standing tree or the stem of 

 healthy trees which have been felled during the previous winter, and 



