My barn was infested with CBees. I read a post on this board
suggesting putting bubble gum in the openings, another suggested
painting them. I tried spraying red paint (spray can, Wal-Mart $0.98),
They I tried expanding foam into the holes (dripped all over, ooozed
out and left interesting effect in th barn ceiling rafters and a real
mess on me).
A neighbor suggested fuel-oil and I bought a gallon of diesel for
$2.75 and sprayed the ceiling using a garden sprayer. Really Soaked
everything in site. Next day - still had bees. So, I sprayed another
gallon (covering some spots I missed and making sure everything was
dieseled completely. Next day, still some bees hanging about. Maybe
fewer, hard to tell as they are not easily distinguishable, one from
the other (save those that got sprayed with the red paint on day one).
Now, a couple of weeks later, there are No Bees in the Barn.
And, I also tried another trick. I broke up a few old roofing shingles
and put them in the bottom of a wide-mouth jar. Then, covered them
with diesel fuel and let it sit like a container of Sun Tea.
Makes a really good stain for OUTDOOR projects kids are not likely to
chew. I put it on and let it soak into the wood, then repeat until it
looks as if the wood will absorb no more. Let it sit in the out of
doors until it dies to the touch, then "install it."
No way to tell yet if the properties of the ingredients of this
"stain" will protect the project for years and years, but I think it
may do quite nicely. It appears that the bird feeder sheds water like
'course, I may expire soon from the toxins . .