Whiteflies are tiny, sap-sucking insects that can become abundant in vegetable and ornamental plantings, especially during warm weather. Despite their name, whiteflies are not true flies but are in the order Hemiptera, related to aphids, scales, and mealybugs. They derive their name from the mealy white wax covering the adult’s wings and body. Adults are tiny insects with yellowish bodies and four whitish wings. Although adults of some species have distinctive wing markings, many species are most readily distinguished in the last nymphal (immature) stage, which is wingless and lacks visible legs.

There are several species of whiteflies, including the greenhouse whitefly, bandedwinged whitefly, giant whitefly, and silverleaf whitefly, among others. Whiteflies normally lay their tiny oblong eggs on the undersides of leaves. The eggs hatch, and the young whiteflies gradually increase in size through four nymphal stages called instars. The first nymphal stage (crawler) is barely visible even with a hand lens. The crawlers move around for several hours before settling to begin feeding.

Whiteflies can cause leaf damage and a host of other problems by feeding on plant sap. They are moth-like in appearance, about 1/16th of an inch in length with an elongated, somewhat triangular shape, and are most often gray-white in coloring. Because of their tiny size, they can be hard to spot. If whiteflies are present, they can be controlled by washing them off with a sharp spray of water. Natural enemies such as lacewings or parasitic wasps can also be effective in controlling whiteflies. These can be purchased at your local nursery or ordered online in containers of 1,000, and sprinkled on the infested plants.