- Yellowing leaves
- Sticky honeydew covering host
- Small, white insects present
There are many species of whiteflies. They are closely related to scales and aphids (more so than flies) and exhibit similar symptoms on host plants. Adults and nymphs feed on the undersides of leaves and produce honeydew that covers the plant, leaving a sticky residue. Leaves often become light-colored or yellow. Adults can often be observed flying around the plant especially when the plant is bumped. Upon close examination, whiteflies are easily distinguished by their small bodies and bright white, waxy wings. Although whiteflies can spread diseases, this is not usually a threat in the home garden.
Females lay between 200-400 eggs in their lifetime. Eggs hatch in one week and begin feeding. Nymphs lose their legs after their first molt and stick flat to the undersides of leaves. Feeding continues for about four weeks until just before they become adults. Adults live for about one month and all generations can be seen simultaneously. Many species of whiteflies cannot overwinter outdoors in Midwestern climates and survive inside on houseplants or in greenhouses.
Whiteflies often enter your garden on transplants coming in from the greenhouse. Therefore, the first line of defense is to inspect new plants for signs and symptoms of whiteflies. If new plants are infested, treat it with an insecticide before mixing it with your healthy plants. Horticultural oil, insecticidal soaps, and neem can kill the immature (nymph) stage of whiteflies. In home gardens, whiteflies can usually be brought to a tolerable level with one to two sprays about a week apart. The abundance of natural enemies in the garden will keep the whiteflies under control. Reserve the other pesticides (permethrin and pyrethrin) for those rare situations when spraying whitefly nymphs fail to control the problem. Keep the garden free of weeds that can serve as hosts that attract whiteflies that can eventually move to your flowers.
Active Ingredients include: Abamectin, Acetamiprid, Azadirachtin, Bifenthrin, Cyantraniliprole, Deltamethrin, Fluvalinate, Horticultural oil (Paraffinic or superior oil) , Insecticidal soap (Potassium salt of fatty acid), Lambda- cyhalothrin, Neem oil, Permethrin, Pyrethrin, Spiromesefin, Spiromesefin
