One of the easiest insect pests to recognize is the whitefly. These aren’t actually flies and look a bit like tiny white moths. You might notice them sitting on the underside of an infested leaf or see them flutter off as you water or handle the plant. They’re easily disturbed but fly only a short distance before they quickly return to the leaf. These sap-sucking insects may become abundant in vegetable and ornamental plantings, especially during warm weather. They excrete sticky honeydew and cause yellowing or death of leaves. Outbreaks often occur when the natural biological control is disrupted.
Whiteflies have many natural enemies, and outbreaks frequently occur when these natural enemies have been disturbed or destroyed by pesticides, dust buildup, or other factors. General predators include lacewings, big-eyed bugs, and minute pirate bugs.
Signs of a whitefly infestation can include:
- Tiny nymphs on the underside of leaves.
- Sticky honeydew on leaves, on fruit, or beneath plants, or a covering of black sooty mold.
- Yellowing, silvering, or drying leaves that have whitefly nymphs on them.
- Deposits of white wax with some whiteflies.
Protect natural enemies such as lacewings, lady beetles, and mini-wasps.
- Avoid using pesticides such as pyrethroids, organophosphates, carbaryl, or foliar sprays of imidacloprid.
- Prevent dusty conditions.
- Keep ants, which protect whiteflies from natural enemies, out of plants.
Use hand removal and traps to reduce whiteflies.
- Prune out isolated infested leaves when you first detect them.
- Hose off adults or use a hand-held vacuum.
- Install ready-to-use, sticky-coated yellow traps or make your own. Use one trap for every medium-size vegetable plant.
- Promptly destroy infested annual plants when flowering or fruiting ends.