One day we were assembling a roof section using Lexan Corrugated polycarbonate panels. The mosquitoes were pretty hungry and entering our shop to feast. West Nile is pretty wide spread in Manitoba and elsewhere and a few have gotten quite ill so I decided some "DEET" would be better than falling ill. I sprayed myself too close to the panels I guess because the next day I noticed the Lexan had cracked around a couple of TEK screws and you could see where the repellant had been sprayed on the polycarbonate. It had turned opaque and had hairline cracks. In short is was ruined. This is not a warranty issue or any design problem with the Lexan. There must be some kind of petrochemical in the Deep Woods mosquito repellant that reacts with the polycarbonate. General Electric Plastics warns against cleaning with petroleum based solvents etc.. Joy dish detergent works and I sometimes use Mineral Spirits  to get tough marks off such as marker pen lines.