Block the bugs—and so much more! Our Bug Shield plastic mesh bug screen catches insects of all kinds, as well as stopping potentially damaging fungal spores. Use it on your fans and ducting, as it is suitable for both intake and exhaust purposes. The Bug Shields feature washable materials, an elasticized opening, and an adjustable drawstring to seal off a perfect fit. Use it on your fans and ducting, as it is suitable for both intake and exhaust purposes. The Bug Shields feature washable materials, an elasticized opening, and an adjustable drawstring to seal off a perfect fit.