Seeing Charles' post regarding spiders reminded me of a remedy for ants in the campground.
While camped this summer at a California state beach campground, I noticed that almost everyone else had a white substance sprinkled on the ground around their tires
and any other part of the trailer/RV touching the ground. I had seen this before, but not as extensively as this trip. (We had never had ant problems in many previous trips at this same campground.)
I had always thought that the white powder was boric acid, but come to find out, it is diatomaceous earth. This is the same product used in one type of swimming pool filter. It is fairly benign--recommended only that you use gloves when applying and don't breath a lot of the dust--it contains crystalline silica. The product was sold at the campground store in baggies, repackaged from the original ''swimming pool'' pack. The DE supposedly chews up the feet of the ant rascals so they don't attack your trailer.
We never had an ant problem. But our son did, big time, in his trailer at a nearby site---but a sprinkling of the DE got rid of the trails in short order!