120 



THE HOP. 



which are placed on the twigs of the pium, usually in 

 crevices near the buds, and in this stage the insect 

 passes the winter as before indicated. With the figures 

 which are given of the different stages of the insect, no 

 description is necessary and in fact all hop growers an 

 familiar with the appearance of the green lice. 



Natural Enemies. — We have already mentioned the 

 important part which the natural enemies of this insect 

 play in its economy. In general, we may say that were 

 it not for the natural enemies of plant lice and for oc- 

 casional spells of extremely hot weather, all living 

 vegetation would be destroyed by them. A great 



