Keep the bugs from spoiling your fun with ExOfficio's BugsAway Impervio Shirt. Its lightweight, moisture wicking fabric will keep you dry and comfortable and repel bugs at the same time. . Quick drying, lightweight polyester fabric with Insect Shield. Insect Shield with permethrin effectively repels mosquitoes including those carrying West Nile virus and malaria, ticks, ants, flies, chiggers, and midges no see ums. Invisible and odorless Insect Shield is tightly bonded to the fabric fibers and lasts 70 washings. Stretch fabric moves with you. Rolled forward shoulder seam to decrease chafing. Wicking fabric keeps you dry. Tagless label. Natural fit: lightly shaped to the body for mobility and comfort.