Bald faced hornets

Bald-faced hornets

5767  Hi my name is Diana and I live in Tecumseh Ontario and it is mid August. I have a Manitoba maple infestation of wasp like bugs that fly and sting. They are burrowing in the trunk of the tree.  There is no visible nest near them, yet they are swarming and burrowing into the trunks crevices from the ground up to  about 7 feet. We have a tree  that is approximately 20 feet away that has just recently died we’ve been told of Dutch elm disease, but I noticed these bugs in that tree as well.  There are bored holes throughout the trunk.  We thought the tree was in distress because of draught conditions here but it didn’t matter how much we watered it didn’t rebound.  Both trees looked very healthy in April /May.  The picture I am sending is of a medium sized bug… There are smaller ones and there is also a much larger one that I have seen where the body is almost 2 inches longer. 

These are bald-faced hornets, Dolichovespula maculata (Hymenoptera: Vespidae). They do not bore in trees, but may thoroughly investigate any crevices/cavities for other arthropods to prey upon. At this time of year, they still are primarily carnivorous, seeking out protein to feed their young. See http://tinyurl.com/htdelhs for more detailed information. Ed Saugstad, retired entomologist; Sinks Grove, WV.