If you live in the south, you have had to deal with Dirt Daubers. Last spring I discovered their tel tale dirt tracks going into the two vent holes in my Mercury 115 engine cowling. I was able to remove about 2 pounds of nests & then looked for a way to eliminate/deny them access. A golf tee top fit almost perfectly in the hole. No more problem, except to remember to remove them before I pull out of the garage.