Forgot to mention, the box is fiberglass, there was no wood or food in there, and it was pretty dry. There was a cardboard box (holding spare rudders), which was damp, but wasn't showing signs of having been ant lunch.

I do have wood under the box, spanning across the trailer to support the middle of the box, but that is 2-year old PT wood and I'd like to doubt that the ants would be eating that and surviving.

They were the big black ants, the bigger ones were 3/4 inch long. Some of them had a brownish color to their big section (in case we have any bug experts here).

Come on, no poisonous snake stories???

Mike