If it's the enclosed vent with a grill, you have to remove the whole thing to access.
Pull off the exterior cover to expose screws. Remove those and you can reach into the hole. DH pulled out most of the buildup by hand, but have a trash bag handy, because we found a wad larger than a softball. Then he finished it off with a vacuum.
Since our dryer got fried last year from overheating, we cut out the bottom of the plastic grill. Haven't had a build-up problem since. Nor do we have issues with wasps.
We bought a different type of vent, but haven't installed it yet. Similiar, but without the problem grill.
http://www.rvsupplywarehouse.com/pro...id/243/pid/512