I've had zero issues with using panty hose stretched over my buckets where I had gnat problems. I secured it with a hair tie so I could easily take it off, because tape wasn't giving me a nice enough hold. Excellent ventilation. Using other stuff was reducing my air flow too much and I was getting more mold than I am comfortable with, as I live in a place where mold takes root extremely easily, not just in my beetle housing/substrates. If you don't want to pay a lot for panty hose, many costume/fabric stores will sell a similar, thin gossamer fabric that should work in the same way. Good luck!