THE INSECT WORLD. 



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trees. Some forms live in blackberry and raspberry canes, 

 others in grasses ; I have taken a species from alder, and in 

 fact a very large number of plants are infested by these boring 

 Hymenoptera. The largest of our species is the ' ' pigeon Tre- 

 mex," T. coluniba, the larva of which attacks quite a consider- 



FiG. 430. 



Pigeon Tremex, T. columba. — a, larva, with young larva of Thalessa fastened to its 

 side ; b, its head ; c, d, female and male pupae ; e, female. 



able variety of trees, including maple, elm, hickory, and beech, 

 and bores into the solid wood, usually when the tree is beginning 

 to die, or is even dead, but not decayed. 



Dealing with these insects is always rather a difficult matter, 

 because we have no means of getting into the infested plants with 

 insecticides. We are again rediiced to farm practice, and must 

 arrange our methods of cultivation in such a way as to reach and 

 destroy the insects by depriving them of food. Thus, with the 

 Phvlloeciis infesting blackberry, if the canes are topped about 

 midsummer, or a little before, the larvae never mature, because 



