Insects injurious to the Willows and Pines. 185 



730. The Willows have 99 species of insects feeding upon their wood 

 and leaves, a very large number being gall-insects, plant-lice, and 

 leaf-rollers. Of the remaining deciduous species, there is no one but 

 that has several insects upon its leaves, or other parts, and there is 

 perhaps not one that wholly escapes alive when these are in excess. 



731. We next come to consider the coniferous species, some of 

 which suffer severely, especially when their leaves are attacked, 

 because these do not put forth new leaves again, as do most of those 

 enumerated, and when the leaves are stripped off, the tree must die. 

 They can not sprout from the roots, and seldom put forth side 

 branches to save life when severely injured. Taken as a whole, 

 coniferous forests are much more liable to general ruin when attacked 

 than others. 



732. The Pirns are liable to attack from about 110 species, of 

 which about G2 belong to the 1st class, 16 to the 3d, 21 to the 5th, 

 8 to the Cth, and 2 to the 7th. Of the 1st class are many species 

 of wood and bark-borers, that are generally more liable to attack 

 old trees that have passed their prime. 



rr 



115. Pine Weevil (Hylobus ). 



733. The pine weevil is a very destructive insect, breeding un- 

 der the bark, but doing the greatest injury after it has com.' to 

 the perfect form. It then attacks the young trees, generally those 

 of from three to six years of age, eating out the terminal shoot, the 

 buds and the young stems. It is not much inclined to fly, and in 

 very hot weather, as also in the cool of night, it conceals itself 

 among the herbage and litter on the ground. 



