This idea / product has been out for a very long time but I thought I'd post it anyway in case some people have never seen it.
I saw a post about Stink Bugs
on the Roadtrek Yahoo group and thought it would be a good idea start screening any potential bug openings on my Class B Van.
You'll see these Mud Dauber Screens in RV parts stores:
The screens attach to the furnace vents with springs and the kit comes with a small tool to help put the spring in place.
It's not too difficult to get the screens and springs in place.
Last Spring, during a really heavy rain storm I saw some water in the RV on the floor where the furnace is. I don't see the water after washing the van or normal rains but I figured I put a small bead of high heat caulk on the top and sides of the exterior furnace vent anyway. It probably would be better to take it all apart and re-seat the exterior vent but if the combination of the new screens and the caulk prevents the water from getting in then that's good enough for me. The high heat caulk is red and it looks good if done neatly. I used tape to prevent a mess