Where do tree wasps nest ?

[peterbolson]

I always thought it was in trees, but I've been watching a lot of them going in and out of a hole in the wall of a shed in my garden ( see below ). There are plenty of suitable trees around so why should they choose this site ?

[eucera]

Tree Wasps (D. sylvestris) are well known to nest in cavities as well as in exposed aerial locations.

[peterbolson]

Thanks eucera. That's very interesting. They are definately the commonest wasp around here at the moment - I'm seeing them everywhere.