Here's a tip that will not only keep your closet free of pesky moths, mosquitoes, and flies with nary a sniff of toxic moth balls, but will also leave your small space smelling pleasantly fragrant:
1 cup cedar shavings (available at pet supply stores)
1/4 cup each southernwood (also known as lemon plant), peppermint, lemon verbena, thyme and rosemary
1/8 cup each whole cloves, lemon peel and peppercorns
An economical and common solution is to add the concoction into sachets, but I personally like to use white plastic wiffle balls ($1.50 at most any sporting goods/toy store) to hold the fragrant mixture. Puncture a small hole through the top of plastic ball, thread some fishing wire though or use small screw-in hooks, fill halfway full, and hang a couple of these in the closet for an effective insect deterrent that will leave your clothes and place smelling oh-so-nice.