Insect Enemies of Trees 



197 



nized by its wide, flattish body, and usually dark appear- 

 ance. Having attained to full size in the trees, they form 

 cocoons among the foliage or on the stems, and remain in 

 this condition until the following spring, when, in April or 

 May, the perfect insects make their appearance. The male 

 is considerably smaller than the female, while the full-grown 

 caterpillar, which is of a greenish-yellow colour, with a row 

 of black spots on either side, is about an inch long. The 

 remedial measures are not at all easy, especially when a 

 large number of trees are attacked, but single specimens 

 may be entirely cleared by shaking the caterpillars into a 

 sheet placed beneath the tree. 



The Larch Aphis (Adelgis laricis) and Giant Sirex 



(a) WILLOW BEETLE (Phyllodecta vulgatissima), AND (b) ITS LARVA 

 Magnified 5 times 



(Sirex gigas) are both, more or less, harmful to the larch. 

 The latter is a formidable and splendid insect, which is, how- 

 ever, not very abundant in this country. 



Generally felled trees, or such as are somewhat sickly, 

 are chosen by the female in which to lay her eggs. These 

 are deposited beneath the bark by means of the powerful 

 ovipositor, and in course of time the whitish cylindrical 

 maggots make an appearance, and with their strong jaws 

 form large borings in the affected tree. 



Cutting down and burning infested trees is the only 

 practical remedy. 



The Willow Beetle (Phyllodecta, vulgatissima) causes 



