4 
SOME TREE-DESTROYING INSECTS. 
marked tussock caterpillars, larch sawfly grubs, and the' grubs of 
poplar beetles. 
Fig-. 2. The tent of the fall web-worm. 
No general statement can be made concerning the life cycles 
of these forms. For example, the first six mentioned have only one 
generation during the season, while the poplar beetle has several. 
The first five go through the winter in the egg stage. The larch 
sawfly hibernates as a larva in its cocoon in the ground, while the 
poplar beetle hibernates as an adult in the ground under stones and 
rubbish. 
