Nope, those little buggers can get thru the holes in the airlock. They must just like the smell better in that jug than in the others. If you are infested withthem, there are stories on here about sucking them out of the air with a shop vac. I usually take a plastic bottle, usually one of my real lemon bottles, cut the top off, pour a little wine in the bottom, a drop or two of dishsoap in the wine after you put it in the bottom, and invert the top half of the bottle onto the bottom half. They can find there way in, but can't find the way out. When you catch a bunch of them in there, you can either throw the bottle away or wash it out and try again. Arne.