Those of us in the south are well aware of the damage dirt dobbers can do. They will build their nests anywhere and love to go into small openings to build their nests. While cleaning the Texoma salt & gunk off my engine with 1/3 water,1/3 Hydrogen peroxide, & 1/3 white vinegar, I noticed a trail of dried mud going into the cowling of my Mercury engine through two small openings (ONE ON EACH SIDE) at the top rear of my cowling. Although it was difficult, I pulled several nests & partial nests from inside the cowling. To prevent them from re-building, I pushed the head of a long, bright orange golf tee into the opening. Problem solved! To remind myself to re-install the plug, or to undo something I have done, I hook a small "D" link to my key float to remind me.