On Jun 24, 10:46*pm, wrote:
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.

Wait until night, then duct tape all the cracks except one small
hole. Stick the nozzle of a spray can of insecticide in the small
hole, start spraying, and beat on the steps. If they can't get out
the spray will get them all.
Red