Is A Whitefly Really A Fly?

Whiteflies can be found on garden plants and houseplants; are they really flies?

As with most insects, there are different types of whiteflies. In Virginia, we generally have five different varieties: The Greenhouse Whitefly, the Silverleaf Whitefly, the Azalea Whitefly, the Mulberry Whitefly, and the Banded-winged Whitefly.

What Does A Whitefly Look Like?

What Harm Does A Whitefly Cause?

How Can I Protect Against Whiteflies?

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What Does A Whitefly Look Like?

Whiteflies only grow to be less than 1/10th of an inch long, and are usually even much smaller than that. If you could see them easily, they would look similar to a moth with a yellow body and four white wings covered in a white wax. They aren't, even though their name would suggest otherwise, a fly. They are closely related to mealybugs and aphids, often being mistaken for mealybugs.

Whiteflies live on the undersides of leaves, hiding and feeding where detection is more unlikely. However, if the leaf is disturbed, a cloud of them will stir up and fly around before returning to the leaf.

As infestations begin, the females will move to new leaves and lay eggs in a semicircular pattern on the underside of the new leaf. The new whiteflies will emerge within days and can become full grown within a month. Additionally, females can lay about 400 eggs over a two-month period. Because of these traits, whiteflies can establish a large population rapidly during warm weather, with year-round populations maintaining indoors or in greenhouses.

What Harm Does A Whitefly Cause?

Whiteflies, like mealybugs, injure plants by sucking the sap from the plant. They have a wide range of plant species they will feed from, with more than 250 different types of vegetable and ornamental plants, which means that it's likely that most of your garden and all your indoor plants are within their diet.

As they suck the sap from the plants, the plants become injured with symptoms such as yellowing leaves, premature leaf drop, leaf curling, stippling (patterns of dots on the plant's leaves), and stunted growth. Some varieties of plants will develop silver leaf, vein thickening, or yellow veins. Basically, the plants begin to decline in health as the whiteflies suck the sap from the plant.

In addition, whiteflies can transmit plant viruses as they move from plant to plant, and they secrete a sugary, sticky substance which promotes mold growth and infestation from other destructive species, such as ants.

With their rapid population increases and their ability to quickly sicken plants in a variety of ways, whiteflies can cause significant issues for outdoor gardens, greenhouses, and indoor plants.

How Can I Protect Against Whiteflies?

Whiteflies prefer hot, dry conditions. Making sure your plants are sufficiently (bot not over!) watered will help deter whitefly populations. If you find whiteflies, remove all infested leaves or entire plants, if necessary, to prevent spread from plant to plant. If you do find evidence of whiteflies, inspect all nearby plants thoroughly for whiteflies and whitefly eggs. Keeping weeds out of the garden will provide fewer places for populations to establish, as well as utilizing reflective plastic mulch.

Chemical control with insecticide is an effective tool, but as whitefly populations are difficult to control once an infestation has begun, several applications may be required to control the spread and eliminate the infestation. If possible, such as in a greenhouse or with indoor plants, quarantining the infected plants will really help minimize spread while the treatment is taking effect.

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To learn about more local Virginia pests, check out our pest library and our other blog posts