Brush up against a plant in your garden, maybe a tomato, eggplant, pepper or okra. If a small cloud of tiny white insects erupt from the plant where you’ve noticed a slight stickiness when running your hands over the leaves, you may be dealing with one of our more ubiquitous garden pests – the whitefly. Here’s what you need to know when identifying and controlling whiteflies.
Not really a fly, this little pest is more kin to aphids and mealybugs, two other notorious pests of ornamental and edible plant species. So tiny we usually overlook them until they create their own cloud, they hide, breed and feed under leaves, adding another layer of evasion to their control. No they won’t come out and fight like men, we have to go after them.
Why are they so numerous at times and not at others? Populations of whiteflies, like other animals and insects, rise and fall in time with weather patterns, available host plants, and the health of plants on which they like to feed. And while very small, even 1/12th of an inch, they usually hang together. You won’t notice just a few cruising your gardenia or ficus plant, but you will react to a cloud of the critters flying above and around your head when their reproductive abilities are rampant.
Different species of whiteflies feed on a range of species, from Citrus to Ash, Giant to Crown whiteflies, using sucking mouthparts to slurp chlorophyll from leaves. Leaving a sticky substance called honeydew, which can in turn create fungal diseases such as sooty mold, whiteflies feeding in sufficient numbers can cause plants to weaken, leaves to wilt, or turn off color, yellow, or fall off. Stunted growth is another sign of whitefly damage, though the easiest way to identify are clouds of them rising briefly from a plant, falling quickly back onto leaves as these critters are not strong flyers.
They like warm weather, which enables some species to reproduce even more rapidly than normal.
Preventing them includes protecting and encouraging the whitefly’s natural predators; spiders, ladybug beetles, and dragonflies are among our beneficial insect populations that help control them. Even hummingbirds help control whitefly populations, another reason to attract them. This also means watch the pesticides, as they, especially insecticides, will wipe out the beneficials faster than the pests. If populations have gotten out of hand and even beneficial insects and birds can’t keep up, try spraying plant leaves with insecticidal soap. Coat leaves including the undersides where the stinkers are hiding and feeding, with the soap, reading and following label instructions. Spray later in the day when it’s cooler as that will be better for your plants and beneficial insects since most of them stop feeding and go “home” to bed. You may have to spray 2 or 3 times for best control, be sure to follow any directions regarding the spacing of applications.
Finally, yellow index cards coated with petroleum jelly (homemade version) or the packaged version in retail stores, will help monitor whitefly populations. If dishwashing detergent is added to the petroleum jelly and spread on small boards painted bright yellow, that will not only attract whiteflies, but they’ll stick to the board and die.
Bottom line, whiteflies are small, annoying pests with the potential to damage edible and ornamental plants. By monitoring populations, keeping beneficial insects and other critters around (and safe), we can mitigate the annoyance factor and provide a degree of damage control.
By Sallie Lee, Urban Regional Extension Agent, Alabama Cooperative Extension System. Contact Sallie at firstname.lastname@example.org.
The Alabama Cooperative Extension System (ACES) operates as the primary outreach organization for the land-grant functions of Alabama A&M and Auburn Universities. ACES is committed to affirmative action, equal opportunity and the diversity of its workforce. Educational programs of ACES serve all people regardless of race, color, age, sex, religion, disability, sexual orientation, or national origin.