Whiteflies are small moth like insects with yellowish bodies and white, waxy wings. The average size of a whitefly is 1.5mm to 3mm and varies with species. Each whitefly species has different wing patterns that can be seen with magnification.
Symptoms and Damage:
The whitefly is a sap-sucking insect which drinks fluid from the plant by cutting into it with specialized mouth parts which causes a plants leaves to turn yellow and appear dry, often times falling off the plant entirely. The insects congregate on the underside of leaves so they may not be visible until the plant is disturbed. Another common symptom is the appearance of black sooty mold which grows on the honeydew (excrement) left by the whiteflies.
Habitat and Life Cycle:
An adult female whitefly lays about 30 to 40 eggs in a circular pattern after which the eggs hatch into the first crawler. They begin feeding at this stage and soon molt losing their legs at which time they attach themselves to the leaf. They then enter a pupa stage from which they emerge as an adult whitefly.
A whitefly will feed on the plant for it's entire life cycle except the pupa stage making it a dangerous pest on both indoor and outdoor plants. The whole cycle from egg to adult happens in just under 40 days.
Control and Prevention of Whiteflies
There are many benefits to avoiding chemicals when dealing with insect invaders. The harsh chemicals in some insecticides may cause more harm to an already injured plant not to mention the possible harmful effects to you or your loved ones.
✔– First choices for attempting insect control.
✔– Used when green don't solve the issue.
✔– Only use when blue options have failed and the plant cannot be discarded.
Prevention✔- Keep plants indoors, keep windows screened and inspect all incoming plants. Regular house plant maintenance will help you to notice any potential outbreaks.
Manual✔- Vacuuming the adults up as they hatch can be used to help control the adult population. Yellow sticky traps can also be used to control and monitor their presence.
Organic✔- Neem Oil Spray, can be used but may require repeat applications as new stages of whitefly life are always active. A mixture of 1 cup isopropyl alcohol to 1 quart water and a half teaspoon of dish soap is said to work with repeat applications.
Biological✔- A number of insect predators which consume the whitefly in one stage of its life or another. The most popular biological choice is a small parasitic wasp called Encarsia Formosa which has been in use in green houses since the 1920s.
Chemical✔- Control of whiteflies can be very difficult because of their large numbers and fast life cycle. Systemic insecticides are the most effective as spray applications require repeat applications because of the insect’s fast life cycle. Any containing thiamethozam, acetamiprid or thiacloprid are said to be most effective. Avoiding chemical sprays are not recommended for whiteflies.
More information on Whiteflies:
Wikipedia - http://en.wikipedia.org/wiki/Whitefly
University of California - http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7401.html