Whiteflies are tiny soft bodied sap sucking insects, they resemble miniature moths or minute white triangles. They are no more than one-tenth inch long. Their feeding is concentrated on the undersides of foliage, where whiteflies remove so much sap that the plants health and progress is seriously hampered. They are most prolific and bothersome in the dog days of summer.
Yellowing and wilting leaves are a sign that whiteflies or aphids are feeding on plants. Inspect the under sides of wilting leaves, clouds of tiny white moths will swarm - that's whiteflies.
Look for honey dew secretions. Honeydew is also produced by aphids , scales and a few other garden pests, the honeydew, in addition to being unsightly will also attract other insects such as ants and flies.
Immature Nymphs may also produce waxy filaments up to two inches long that resemble cotton candy.
Both the nymphs and adults feed on plant juices of most plant species. They also excrete liquid waste called "honeydew." Honeydew is not only unsightly, it gets on foliage and prevents photosynthesis, contributing to the plants early demise.
The waste - honeydew that white flies excrete promotes the growth of sooty mold, a black fungus, which grows on the honeydew coated leaves and fruits. Whitefly feeding also spreads other plant pathogens.
Okra, eggplant, tomatoes, peppers, sweet potatoes, cucumber, and cabbage-family crops, as well as many ornamental plants are all affected by whiteflies.
Whitefly Life Cycle
Female whiteflies lay their eggs on the undersides of leaves, the eggs hatch very rapidly, generally in 2 to 3 days into tiny, mobile scales and begin feasting on plant juices immediately.
The scales molt to a legless stage within a week. After multiple growth stages the nymphs remain in a pupal stage before emerging as adult whiteflies. Their entire life cycle is 20 to 30 days, so there are numerous successive generations overlapping each season. In greenhouses and warmer climates their regeneration continues unabated year round.
Control of Whiteflies
Adult whiteflies can be caught on yellow sticky traps. Spent adult carcasses should be vacuumed from leaves , floors in indoor environments. Remove any infested foliage. Reflective mulches [Aluminum] in outdoor environments are advisable if whitefly is a severe problem. Studies have proven that they reduce whitefly populations. See: Combining reflective mulch and host plant resistance
Parasitic wasps will help control whiteflies in green houses, outdoors you might want to attract native parasitic wasps and Ladybugs. Diverse gardens that include a symbiotic mingling of flowers and vegetables are a poor environment for whitefly and other pests as they also attract many natural predators,Lacewings and Ladybugs in particular.
Neem Oil , horticultural oil, insecticidal soap or garlic oil will help control whitefly populations. Horticultural oils and insecticidal soaps will smother them at any life stages.
Try to avoid pesticides, many strains are resistant, but their predators and other beneficial insects such as pollinators are not. Spray with Broad-spectrum insecticides, such as Pyrethin only as a last resort.