Jd, I suspect the entire bat population of Actun Tunichil Muknal might not even put a dent in the mozzie population of my "backyard" when theyre holding one of their conventions, but there would certainly be plenty of hors d'oeuvres to go around...speaking of traps...we have found when throwing a party we can protect the majority of our guests by placing a few buckets of iced beer in strategic locations at the peripehry of the property. This inevitably draws a few people to each of those locations and they'll greedliy sit on that beer stash as their own. This tends to draw the lil bloodsuckers to the outliers and leaves the central area of the party uninfested. A periodic refill of the buckets pretty much ensures a bug free night. I should add that we find that we constantly have to invite new people to our parties, not only to meet new people, but to provide fresh meat as the veterans of previous soirees know to circle the wagons at the buffet table and main bar.
Ambergris Caye 
AmbergrisCaye.com