Little Screen to put over 6 inch vent?

I had a bug problem last time and I'm trying to prevent it this time. I am pulling air out of the room and into the attic via a six inch hole in the ceiling... the fan is actually in the attic and just sits nicely in the 6 inch hole. Today I went to Home Depot to see if I couldn't find some sort of screen to put over the top of the fan so bugs can't try to call into my garden - no luck...didn't see anything that would have done the job. Do you guys know of anywhere that carries a product like this? It's probably unlikely that the bugs will crawl through that six inch hole considering tons of air is usually flowing through it, but I'd like to be safe.

heh heh. This is what you have a girlfriend for:
Send her to the store for a couple pair of QUEEN SIZE pantyhose. It will be obvious if she is young and lanky that they are not for her. You, on the other hand, would garner a few looks buying such an item.
Secure at least 2 layers of said pantyhose over the vent.
Voila, problem solved for about $4.
('Nude' works better than 'suntan' :D)

Ahh, Stinky, you simply are the best.

Here I am looking at freaking $50.00 Hepa filters, that look extremely hard to cut etc. What a sweet idea once again! You think several layers of the pantyhose would keep out even those little spider mite fuckers? Thanks for the tip.

P.S My girlfriend is tiny, I can't wait to hear the reaction she gets at the store.

Spoke with the guys at the Hydro Store... they have a product that's over a bill it's a Hepa Filter that keeps all the Powdery Mildew\Mold out... he said the pantyhose will work just fine for bugs, not as well for mildew and mold but to be honest I haven't had a problem with that stuff anyhow so I'm gonna just continue on with the pantyhose plan until I see some sort of problem in the room.

Spider mites can't fly, so they probably won't get in anyway.

One of my friends in college that was in the Marine Corps ROTC was always having to buy pantyhose to polish his shoes. I guess they work the best, who knew? Anyway, we always got a laugh out of that. :)