
How To Get Rid Of Whiteflies So They Don’t Destroy Your Plants
Whiteflies are tiny insects that affect many different types of plants, including trees, vegetables, ornamental plants, and houseplants. “Multiple generations can be present at once, so they can be difficult to control if an infestation isn’t caught early,” says Rafia Khan, PhD, assistant professor and extension entomologist at Texas A&M AgriLife Research and Extension Center. “They are sap feeders, which use their piercing and sucking mouth parts to take plant juices.”
Related to aphids, scales, and mealybugs, whiteflies can cause significant harm in greenhouses. But they also can wreak plenty of damage on garden and houseplants. They especially like soft, new growth, and their feeding results in stippling of leaves, yellowing foliage, and premature leaf drop, says Khan. Some plants may not survive an infestation.
Outdoors, natural predators, such as lacewings and lady beetles, help keep whiteflies in check. But whiteflies may hitchhike indoors on a newly-purchased plant because their eggs are nearly microscopic and easily missed, or you may bring a hidden infestation indoors in the fall if you take plants outside for the summer, says Khan.
Identifying Whiteflies
Whiteflies go through egg, nymph, and adult stages. You likely won’t see their teeny eggs on the undersides of leaves. Once hatched, the nymph stages are about 1/32-inch long and attach to the plant for feeding. “The nymph stages are immobile and resemble scale insects,” says Matt Bertone, PhD, director of the Plant and Disease Insect Clinic at North Carolina State University. “Although closely related to scales, they are not the same thing so properly identifying them is important.”
The adult stage of whiteflies look like moths and are 1/16-inch long. Their white coloration comes from a dusting of wax on their bodies, says Bertone. Adults congregate and swarm up in clouds when an infected plant is disturbed; this doesn’t occur with scale insects, which are stationery.
Whiteflies also secrete honeydew, which can lead to the growth of sooty mold, which reduces photosynthesis and overall plant health, says Khan. Some species also transmit plant viruses.
How To Get Rid Of Whiteflies
If you have suspect whiteflies on a garden or houseplant, try these steps for control:
- Inspect plants regularly. “Scouting for these insects on garden and houseplants is the best thing you can do to protect your plants and catch problems early,” says Khan.
- Use yellow sticky traps for monitoring. But be aware that while sticky traps can alert you to an infestation, they won’t control one.
- Prune off affected leaves or stems. This may halt the infestation if you detect it early enough, says Khan.
- Blast insects off with the hose. “A high pressure spray can physically remove them from garden plants,” says Kahn. You’ll need to periodically to deal with newly-hatched whiteflies.
- Treat with insecticidal soap, neem oil, or horticultural oil. Cover every surface of foliage on both top and bottom, says Khan. Re-treat according to label directions, but typically you will need applications every 5 to 7 days over the course of several weeks.
- If you’re still fighting an infestation, try a systemic insecticide. These are usually granules that are watered into the soil. Choose one that’s labeled for whiteflies and the type of plant you’re treating.
- Know when to cut your losses. If you have attempted treatment on a houseplant unsuccessfully, it may be time to toss the affected plant so that others are not infected, says Khan.
How To Prevent Whitefly Infestations
It’s not foolproof, but these tips can help reduce the chances you’ll bring home an infestation in the first place:
- Isolate new houseplants. When you buy a new houseplant, keep it away from your others for a few weeks to ensure you’re not introducing whiteflies or other pests to your entire collection, says Khan.
- Keep houseplants indoors. Although you may think house plants benefit from a summer outdoors, you risk the introduction of pests such as aphids, mealybugs, and scales. These pests may then be brought back indoors on the plants in the fall, says Khan.
- Treat outdoor plants before bringing them in for the winter. If you must bring outdoor plants inside for the cold weather months, spray them down with a hose first, then proactively treat with an insecticidal soap. Or consider using a systemic insecticide that’s watered into the soil, but read the label to ensure it’s okay to use on the type of plant you want to treat.