For some reason, wasps continue to think it's a good idea to enter a building without retaining any memory of how to get back out again. Windows in particular seem to confuse them, which means that even when they decide they want to leave you alone, they can't actually figure out how to.
The wasp flap, built into a window, is a convenient portal to the outside world. Unlike cat flaps, it will be hinged only one way; this will help prevent all and sundry insects using your abode as some kind of central meeting point.
Some kind of lure may be necessary to encourage use of the flap, though I haven't yet thought out a way to do this that wouldn't result in wasps congregating around the outside of the flap.
Also, I think it would be interesting to see how long it would take for spiders to realise it's a good place to hang out for food.-- -alx, May 10 2002 Ethology of wasp sense http://salmon.psy.p....HTM#Digger%20waspsWho moved my … ? [reensure, May 12 2002] Perhaps bait them with the sweet odor of rotten fruit, and add a little suction. Excellent for cars also.-- pottedstu, May 10 2002 But you'd need a pretty big flap for a car to get through.-- waugsqueke, May 10 2002 <Groan> </Groan>-- phoenix, May 10 2002 Have you tried a screen over the window? Or negative ventilation in the garage while parking the car? How about a giant spider web over your whole house, or a "NO WASPS" sticker on every entry point? How would you get the wasp to use the flap?-- em-tae, May 11 2002 Trouble is, the best bait for mud is new carpets, so it's more likely to come in the flap than go out.-- pottedstu, May 11 2002 Why not just blast it with a dose of Raid?-- DrCurry, May 11 2002 I thought this was going to be a W*A*S*P Flap-- thumbwax, May 11 2002 Folk figured the wasp thing years ago -- just embed funnels in your roof fascia and wasps will use these as entry points rather than an open window. I believe they are precision flyers and don't normally seek open windows or doors.-- reensure, May 12 2002 I've yet to see two wasps have a mid-air collision during precision formation maneuvers, though I did see a death spiral end quite badly once.-- thumbwax, May 12 2002 random, halfbakery