<p>Bed bug nymphs can get through regular zippers, but there are tightly made zippers that are being used on some mattress encasements now that are supposed to be bed bug proof. Sally, your idea of a plastic cover for suitcases would work it it had these zippers. I know someone who acquired bed bugs on their carry-on suitcase that was stowed under the seat of an airplane. People are also starting to worry about their luggage in the cargo hold.</p>