Nymphs and adults suck plant juices from citrus, greenhouse foliage plants, ornamentals, and vegetables. Their feeding weakens plants; they also secrete a sticky, sugary substance called honeydew. Sooty mold, a black fungus, grows on the honeydew-coated leaves and fruit. Whitefly feeding can also spread viral diseases.
Related: 10 Most Destructive Garden Insects And How To Get Rid Of Them
Whiteflies rest in huge numbers on leaf undersides and fly out in clouds when disturbed. The adults are are tiny with powdery white wings, and their larvae are flattened, legless, translucent, 1/30-inch scales on leaf undersides. Their eggs are gray or yellow cones the size of a pinpoint.
Whiteflies are commonly found in greenhouses throughout North America; also found outdoors in warm regions of California, Florida, and Gulf states, and areas on the West Coast. Find out the best, organic methods for controlling whiteflies below.
WHITEFLY LIFE CYCLE
Females lay eggs on undersides of leaves; these hatch in 2 days into tiny, mobile scales; while continuing to feed on plant juices, scales molt to a legless stage in a few days. After several growth stages, nymphs rest in a sort of pupal stage before emerging as adults.
Most whitefly species require 20 to 30 days for a complete life cycle at room temperature, fewer in summer. Numerous overlapping generations per year, continuing all winter in greenhouses and warm climates. In cold-winter areas, whiteflies may infest plants outdoors during warm summer weather, and cold weather will kill them off.
Related: 14 Natural Ways To Control Garden Pests
HOW TO CONTROL WHITEFLIES
There are many ways you can control them outdoors. You can catch adults on yellow sticky traps or even just vacuum adults from leaves and then remove the infested leaves.
In a greenhouse, you can release Encarsia formosa parasitic wasps to control the greenhouse whitefly; and outdoors, you can attract native parasitic wasps and predatory beetles with plants like dill, yarrow, coriander, and vitamin-rich parsley. (Also check out 10 Insects You Should Actually Want Around Your Plants.)
If the situation worsens, you can resort to spraying with insecticidal soap or garlic oil, or read up on how to make a natural pest spray that actually works with ingredients like garlic, onion, and hot pepper.