Although they have fallen into disfavor because of mosquito resistance and other problems, chemicals are still the fastest and most effective way to suppress mosquitoes. The thrust of nearly all University research in this area is on the development and evaluation of narrow spectrum insecticides that selectively kill mosquitoes with minimal injury to natural enemies and nontarget species. Promising new developments include insect growth regulators, which interfere with the growth processes of the mosquito larvae, juvenile hormones, mosquito attractants, repellents, and other substances derived from natural products.