The International Cessna^® 170 Association

Gentlemen,
We plug the air vents, and about everything we can to prevent these nest builders our of our aircraft. I was worried about the fuel vent on the 170B. It's hard to reach and install a slip on cover. The owner and I came up with the idea of using a "Dolly Parton" over the center/top fuel vent. I rigged one with an small eyebolt in the top and now we use a mop handle/hook to install and remove the thing. For the engineer type, a "Dolly Parton" is one of those things you put over your outdoor faucet to keep the faucet from freezing. Works great, in the hangar, but the wind would blow it off outside.

There is a chemical that can be sprayed on the aircraft that repells these pests. I am using it in my hangar, it seems to work.
Kimble

OK. I know I'll be "busted" by my critics, but....what the Hey? It sure works well. (OK. I'll say I remove it before flight!)
I noticed the fine screen on the bottom of the pick-up tube inside the quart can (any size actually) of TCP is a nicely shaped "bucket" made of stainless screen. In fact it's exactly the same size as the I.D. of the gooseneck fuel vent. The rim of the "bucket" fits the gooseneck so well that even if I did forget to remove it before fight, it cannot be blown into the tube.
No modification or other tinkering necessay. No insects can get into the vent either on the ground OR in flight. (At least I don't think they can get in there in flight. I wouldn't know for sure since I always remove mine for flight.)

(And, oh yeah....both my fuel caps are vented just for good measure.)