Bald-faced Hornet

Description:

also known as the White-faced hornet, they are from the family vespinae, which includes yellowjackets, hornets, paper, mason, pollen, and potter wasps. The worker hornets grow to be 12-14 mm long, whereas the queen (here i share small wonder's photo of one: http://www.projectnoah.org/spottings/111...) can grow up to 18-20 mm long

Habitat:

It was joining the carpenter bees in buzzing continuously around our shed door.

Notes:

I would like to know if they are aggresive? And since i found one, could there be a nest around here?