40 



OTHER COMMON INSECTS 



The larva of the 

 Thalessa makes its way 

 along the burrow of the 

 Tremex borer and fas- 

 tens itself to the body of 

 the borer, where it feeds 

 upon the borer and thus 

 kills it. In time the 

 adult Thalessa emerges, 

 ready in turn to do its 

 part in laying eggs 

 which will destroy more 

 of these enemies of the 

 tree. But if the Thalessa 

 parasites kill the Tremex 



borer before it has eaten 



Figure 40. — Ichneumon Flies. ., ,-, ■, . , * n 



its way through the hard 

 Laying eggs in a tree. , . n ,. 



wood, then all die to- 

 gether, because the Thalessa cannot cut an opening for itself. 



Figure 41. — Adult Horn-tailed Saw-fly. 



Just after laying eggs in a tree. The larvae of this 

 insect do much damage to lumber. 



