Whiteflies
Pest · Commonly affects: Tomatoes, Peppers, Eggplant, Cucumbers and squash, Beans, Cabbage and other brassicas
Whiteflies are tiny sap-feeding insects in the family Aleyrodidae, close relatives of aphids and scale, with the greenhouse whitefly and the sweetpotato (silverleaf) whitefly being the two most common in US gardens. They matter because they build up fast in warm weather, weaken plants by draining sap, and can spread plant viruses that no amount of later care will reverse.
How to identify it
Adults are about a sixteenth of an inch long with powdery white wings, and they gather on the undersides of leaves, rising in a small cloud when you brush the foliage. Look also for the immobile stages: flat, oval, semi-transparent nymphs that sit fixed to the leaf underside like tiny scales, often alongside clusters of pale eggs. A sticky, shiny film on lower leaves, sometimes darkened by black sooty mold, is another reliable sign.
Damage
Both adults and nymphs pierce the leaf and feed on phloem sap, which causes yellowing, leaf curling, wilting, and stunted or reduced growth when populations are high. They also excrete sticky honeydew that coats leaves and feeds sooty mold, blocking light, and several species transmit damaging plant viruses as they move from plant to plant.
Prevention
Inspect the undersides of leaves on all new transplants before bringing them into the garden, since infestations usually arrive on purchased or shared plants. Keep beds free of weeds and old crop debris that shelter whiteflies, space plants for good air movement, and avoid pushing soft, lush growth with heavy nitrogen feeding, which whiteflies favor. Where available, choose vegetable varieties bred for tolerance to whitefly-borne viruses, and rotate susceptible crops so pest numbers do not carry over in one spot.
How to manage it
Catch problems early by hanging yellow sticky cards near plant tops to trap adults, hosing the leaf undersides with a firm spray of water, or using a small handheld vacuum over the foliage in the cool morning when adults are sluggish. Pinch off and bag heavily infested lower leaves, and pull and destroy any plant that is severely colonized or showing virus symptoms rather than leaving it as a source. Protect young plants with floating row covers until they are established, and encourage natural enemies such as parasitic Encarsia wasps, lady beetles, lacewing larvae, and minute pirate bugs by keeping flowering plants nearby and avoiding broad sprays that kill them.
General guidance for US home gardens, focused on prevention and non-chemical control. For a confirmed diagnosis and options specific to your area, contact your local Cooperative Extension office. Page updated Aug 4, 2026.