126 ON THE NATURAL HISTORY OF BEETLES 



towards the root, the bark, or the tender young shoots ; but, in any 

 case, their preference for the apparently weaker growths and con- 

 stitutions holds good, whatever may be the method of attack, and 

 whether their victim be a recently planted seedling or a mature tree. 

 They probably, in the first instance, feed on their prey, and then 

 breed in the cavities which their predacious attacks have made. 



The season when insects are most injurious to coniferous woods is 

 generally from the beginning of April to the end of June, and again 

 from about the beginning of August till the middle or end of Sep- 

 tember, in favourable and mild weather or ordinary seasons. Of 

 course, cold or wet weather may affect their operations, but, as a rule, 

 these are the times of the year during which the greatest havoc is com- 

 mitted. Hot and dry summer weather, especially if succeeded by 

 a cold, dry, frosty winter, favours the dissemination and increase 

 of forest-feeding insects. The warmth of summer fosters their 

 breeding, because by its genial influence their period of trans- 

 formation from the larva state is shortened, and abundance of time 

 is afforded for several broods to mature in succession ; and when 

 the following winter is dry, a superabundant number of insects 

 will be found in the ensuing spring ; while, on the other hand, 

 should the summer season prove wet and deficient in sunshine, and 

 the following autumn and winter be damp, intensely cold, or 

 snowy, the numbers of insects, whose increase had been pre- 

 viously checked by the adverse summer, will be materially les- 

 sened in the following spring, and the destruction to the woods for 

 the time will be proportionately less severe. These remarks prin- 

 cipally apply to insects which affect the bark of pines, especially 

 the silver fir (Plcea jpectinata), and confine their attacks to the tree 

 through that medium, selecting chiefly those old trees the bark of 

 which is not very hard. They direct their attack, in the first 

 instance, to apparently weakly or dying specimens, or settle upon 

 felled timber, feeding upon the stagnated sap of the inner bark, 

 to which they bore, by the aid of their sharply-toothed jaws, in 

 a direction slanting upwards as far as the sap wood, and from 

 thence the female hollows out a perpendicular canal about 3 or 4 

 inches in length in the inner bark, with small niches close to- 

 gether on each side ; in these she deposits her eggs, which are small 

 round white objects, and, having covered them up with a slime of 

 her own secretion, the larvse are hatched in about fourteen days, 

 and they again cut for themselves ramifying passages in all 

 directions, which widen as they proceed, and resemble alphabetical 



