The book Greenhouse Gardener’s Companion lays out hundreds of solutions to controlling everything from aphids to slugs to whiteflies. Also, check this link to a listing of companies that provide supplies for controlling bugs.
Simple tip: If you have a low infestation of Whiteflies convert your dust buster into a whitefly sucker. Simply make the tip of the dust buster yellow (done here with yellow paper wrapped around the nozzle). This attracts the little buggers into the vacuum. Suck thousands of them in minutes!