By Matt Gibson
Whiteflies, also called aleyrodidae, (scientific name is Trialeurodes vaporariorum) are small, white, soft-bodied, winged insects that are closely related to aphids and mealybugs. Whiteflies are pests which are commonly found on indoor plants, in greenhouses, and on tomato crops. Whiteflies are so small, that they are often hard to detect with the naked eye.
Like aphids, whiteflies are usually found in clusters on the underside of leaves. As small as 1/12 of an inch and triangular in shape, whiteflies would be nearly impossible to spot if they were nocturnal creatures and didn’t fly around during daylight hours. Fortunately, whiteflies are active during the daytime, so if you know what plants they like to feed off of and you know what you are looking for, even the smallest whiteflies tend to stick out like a sore thumb.
One of the more common species of whitefly is the silverleaf whitefly, which is slightly smaller and more yellow than many other species, and common to the southeastern states. Whiteflies appear in the mid to late summer when the weather starts to warm up. Ornamental plants and warm weather veggie plants are the most at risk of whitefly infestations.
All species of whiteflies affect a wide variety of plants. Though these are not the only plants that are commonly affected by whiteflies, if you are growing any of these plants in your home garden, you will want to check them regularly for whitefly infestations and act accordingly if you see them congregating on the underside of any of the following plant leaves:
Tomatoes, Bell Peppers, Okra, Sweet Potatoes & Cabbage.
The whitefly sucks on plant juices and produce a sticky, gooey substance called honeydew. If left untreated, the honeydew residue that whiteflies leave on plants could lead to a variety of fungal diseases that could kill off entire crops.
If you notice a sticky residue on your plants, sometimes accompanied by ants, who are attracted to the honeydew substance, then whiteflies have most likely been feeding off of the affected plants for several days. Plants that have been fed on start to wilt and look weak, and are sometimes unable to photosynthesize. The leaves begin to turn yellow or pale, and the plant’s overall growth can be stunted significantly.
The easiest way to identify whiteflies is to find them congregating on the underside of leaves. Sometimes you can catch large infestations before major damage begins to become evident. A dense collection of white spots and a white residue is a dead give away. If you wipe the underside of the leaves with a thumb, all the whiteflies will take to the air, which also makes their presence very obvious. You may also find pale yellow to brown eggs on the underside of leaves during a whitefly infestation. Pale yellow eggs are freshly laid, while brown eggs are just about to hatch. Once the eggs hatch, the larvae appear as tiny white dots with no visible legs.
Whitefly Life Cycle
In the late springtime, adult female whiteflies lay anywhere between 200 to 400 eggs per season. The eggs are laid in circular clusters which hatch anywhere between one week and a full month’s time. Young nymphs overwinter on the leaves of the host plants. Similar to mealybugs, the crawlers move a small distance from the hatched egg before making themselves flat against the surface of the leaf to feed.
The nymphs go through three more stages without moving at all, before moving into a pupal stage. Within a week after the pupal transformation, young adults emerge to start the cycle over again. Many generations occur within a single year. Whiteflies transform from egg to young adult in a period of around 25 days if allowed to develop in room temperature environments. Adults live anywhere from one to two months.
Whiteflies are not usually noticed during the immature stages. Only once they emerge as young adults and start sucking on the juices of the plants, do they start to get noticed by gardeners. The life cycle and perceived dormancy is very similar to scale insects.
Methods for Controlling Whiteflies in the Home Garden
The first method of control that you should try is to blast the whitefly clusters off of the underside of affected leaves with a stream of water from your garden water hose. It won’t eliminate the entire population of whiteflies in one fail swoop, but it will knock off a good bit of the colony that are plaguing your plants. Multiple treatments of these water blasts may be all you need for mild infestations. There is a special tool called the Bug Blaster which can help you make your garden hose treatments even more effective, if you can locate one at your local gardening center or order one online.
Yellow sticky traps are another great chemical-free method of controlling the whitefly population in your garden. These can be purchased at the store and set up in the garden easily in multiple locations. The sticky traps will not only suppress whitefly issues, but it will also help you monitor the severity of infestations.
Releasing natural predators in your garden, such as ladybugs and lacewing larvae can help to eliminate whitefly colonies naturally. There is also a parasite simply called the whitefly parasite that can be released to limit your whitefly populations.
Severe whitefly infestations may require some pesticidal sprays. If you have to go this route to get whiteflies under control, try a short-lived organic pesticide in combination with releasing some natural predators. Use the pesticide first, then release the beasts. SaferSoap is a short-lived natural pesticide that will work quickly on heavy infestations by damaging the outer layers of the adult flies, dehydrating, and killing the adults. Repeat treatments every seven to ten days until whiteflies are eradicated.
Botanical insecticides sometimes work better on whiteflies than chemical treatments. Neem oil, BotaniGard ES, and horticultural oils have all shown fantastic results in treating the common garden pests. Fast-acting botanical insecticides should only be used as a last resort, as natural pesticides have fewer harmful side-effects and will break down more efficiently causing less damage to the environment than synthetic chemical applications.
Try out one of the methods above and be ready to alternate and take on the issue from multiple angles. Whiteflies are persistent pests, but they are no match for persistent gardeners with the proper tools on hand.
Want to Learn More About Whiteflies?
There are many different ways to control and eliminate the presence of whiteflies in your garden. The Rusted Garden illustrates his method in this short tutorial video, which consists of first blasting the whiteflies off of the underside of the leaves with the force of the water hose, which clears off the majority of the whitefly clusters. Then, he treats the underside of the leaves with a mixture of soap and oil in three different cycles, putting five days between each treatment:
This pest control film focuses in on five of the different control methods that are commonly used on whitefly infestations, showing you how to rid your garden plants of whiteflies with several different approaches:
This short tutorial film teaches you how to use yellow sticky traps to catch whiteflies, aphids, thrips, fungus gnats and leafminers, all without using any pesticides or chemicals. Using this simple, easy to use trap technique, you could save a lot of time fighting different garden pests, easily controlling your garden pest populations without harming beneficial insects along the way with chemical sprays and other invasive control methods: