INSECTS INJURIOUS TO CONIFEEiE. 



161 



will serve excellently as a focus of infection. The duration 

 of larval life is very variable, and depends on the climate and 

 the season. As a rule, if the eggs are laid in the spring of one 

 year the imagos make their appearance in the summer and 

 autumn of the year following, live through the winter and 

 lay their eggs in the spring ; or they may appear in the 

 spring and live through the following winter after egg-laying. 

 In any case the life of the perfect beetle lasts a year or there- 

 abouts, and does not, as is the case with most insects, finish at 

 the period of egg-laying. No injury whatever to growing plants 

 of any value is done by the feeding of the grubs ; it is entirely 

 the work of the perfect beetles, which proceed on foot to young 

 trees, preferring Pine, but also attacking Spruce, Larch, Cypress, 

 &c., and occasionally Oak and deciduous trees when pressed by 

 hunger. 



The insects can fly, but hardly ever do so, except at pairing- 

 time. They, therefore, frequent the neighbourhood of their 

 breeding-places, and judicious selection of the site for a nursery 

 away from such localities where the insect breeds will keep the 

 trees free till they are planted out. The beetles ascend the young 

 trees and feed on the bark of the shoots and smaller branches, 

 gnawing out circular holes with shelving sides, which may reach 

 the sapwood. In bad attacks these holes are placed so closely 

 as to coalesce, and thus patches of bark are completely destroyed, 

 the branches or the entire tree being killed. Flow of sap and 

 of resin follows the injury, the latter being often very conspicuous. 

 The trees chosen are usually from three to six years old, but 

 younger ones are not rejected, and those up to fifteen years are 

 sometimes attacked. Specimens can commonly be taken upon still 

 older trees, and they will probably attack any tree the lower 

 branches of which are not more than seven feet from the ground, 

 above which height they do not ascend. They cannot injure 

 old bark, and the damage done to trees above ten years old is 

 usually insignificant. 



The preventive treatment of this insect consists in keeping 

 the forest as free as possible from unbarked logs and trunks, 

 heaps of rubbish and of sawdust, and in preventing egg-laying 

 in the stumps of recently felled areas. This is done by barking 

 the exposed parts of stumps, earthing them over and beating 

 down the earth, or by washing them with an arsenical wash, either 



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