THE ENEMIES OF ENGLISH WOODLANDS 277 



Dr. Somerville, the results of whose labours are published 

 in the Transactions of the Highland and Agricultural Society 

 of Scotland for 1891. It appears that the number of 

 generations or breeds which develop in one season vary 

 with climatic conditions. Where the summers are long and 

 warm, as many as three broods may occasionally be reared 

 in one season, or, where they are short and cold or wet, not 

 more than two, or possibly only one brood may be brought 

 to perfection. In the south of England it may be taken for 

 granted that two broods are always developed, and in long 

 summers three may occasionally occur. In the former case 

 the beetles emerge from their winter quarters early in 

 March (we have found them boring into felled trunks on 

 the 10th of March). The earliest laid eggs hatch out in a 

 few days, and mature beetles from these will appear in May 

 or June. The majority of these beetles do not appear to 

 bore into small shoots, but proceed to swarm and raise a 

 new generation at once. 



The second generation appears in August, and the 

 majority proceed to the crowns of healthy pines and bore 

 their way into the pith of the same year's shoots. They 

 feed there for two or three weeks, boring their way up until 

 they have approached the terminal bud, or, in the case of 

 a long shoot, until they have satisfied their appetites. 

 They then leave by their entrance, or by making an exit 

 hole at the upper end of the boring, and find their way to 

 the base of old pine stems with thick coarse bark, where 

 they bore a short gallery, sufficient to shelter them through 

 the winter, and there hibernate. But there is every reason 

 to believe that a few of the August brood swarm and raise, 

 or attempt to raise, a third generation. In long warm 

 summers the second generation will appear early in August, 

 and their progeny have at least two months (the normal 

 period of development) to mature. Probably the presence 

 or absence of suitable breeding material may make a great 

 deal of difference in the habits of these and other beetles 

 as regards the number of generations in one season, and 

 absolute agreement amongst observers in different districts 

 and among different conditions can scarcely exist. 



But the main point in practical forestry is to discover 



