I have a set of three wooden steps resting on concrete outside a
door. The structure is completely enclosed, but with lots of
cracks where hornets can get in and out.
I am afraid to try to remove any of the boards to gain access. I
can stick a tube into the interior through a crack
At night, I tried pouring a small amount (all I happened to have)
of ammonia through the tube into the interior yo see if the fumes
would kill them or drive them out. It didn't happen.
Any suggestions will be appreciated. Thanks.

*Sevin* powder.