266 PROTECTION AGAINST INSECTS. 



however, no breeding chamber, as copulation takes place out- 

 side on the trees. The ? prefers dying or felled timber with 

 rough bark, windfalls, stumps and broken trees. On standing 

 trees the lower coarse-barked portion of the stem is selected, 

 as the brood-galleries are entirely limited to the bark. If no 

 old wood is to be found, the beetle attacks young poles. 



The larvae hatch in April or May, in about 12 to 20 days 

 after the eggs have been laid ; they pupate in June or the 

 beginning of July. 



The beetles appear at the end of June and in July. Some 

 later ones may emerge in August. The beetles which develop 

 early, in June in mild localities, produce a second brood, which 

 is ready by the end of August, and attacks the terminal shoots 

 of the tree and branches ; those which come out later do not 

 pair but at once commence their destructive work in the 

 crowns of the trees. Thus the whole development of the 

 beetle may last from 60 days under very favourable circum- 

 stances, to 80 days. In order to hibernate, the beetle bores 

 into the rootstock or roots of standing trees, sometimes into 

 stumps, often into the thick bark at the lower part of the 

 trunk. 



The generation is either single or double. The insect is very 

 numerous, and widely distributed ; it is common in almost 

 every pinewood throughout Britain. 



c. Relations to the Forest. 



The beetle generally attacks the Scots pine, but also the 

 Weymouth and cluster pines and other species of pines. It 

 has also been frequently observed on the spruce; rarely on 

 larch. 



It attacks old and young trees, but prefers the former, and 

 is very rarely found in woods less than ten years old. Woods 

 between thirty-five and forty years old are chiefly attacked. 

 The insect does three kinds of damage. 



First of all the beetles and larvae attack the bark and bast. 

 The beetle makes longitudinal galleries, with one to three air- 

 holes, which may be straight, but generally commence with a 

 characteristic hook-like bend. The entrance-hole is usually 



