I wouldn't think it would be likely to damage fabric, any more than the cold of your freezer would. But just in case, one might want to put something like a cotton towel on top of the kilt or other clothing, and the dry ice on top of that. In normal room temperatures it would vaporize completely pretty quickly, and the idea here is not actually to freeze the bugs and buglets but to gas them. In a totally "green" way that won't harm family members or pets should the seal fail on the bag.