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 a duck.
'course, I may expire soon from the toxins . .