Whether you have a few African violets, a fiddle leaf fig tree, or a house full of tropical plants, you know that regular care keeps all your houseplants healthy and happy. Despite your best efforts, your indoor garden may become infested with insects or mites from time to time. A few bugs will not cause much damage, but if left untreated, they will multiply and turn your favorite potted plant into an unsightly mess, or even kill it. But don’t be alarmed. Most common houseplant pests are easily controlled with a few simple techniques and a little perseverance.
“When tackling houseplant insect pests, the first step is to ask yourself how much you value the plant,” says Laura Jesse Iles, director of Iowa State University’s Plant and Insect Diagnostic Clinic. “There are no quick fixes and it will take time and dedication to manage the pests.”
If you choose to treat rather than discard your infested plant, Iles suggests isolating it to prevent the problem from spreading to your other plants. Here is how to get rid of the most common houseplant pests.
Scales are small, soft-bodied insects that feed on plant sap. As they feed, tiny crawlers (the immature stage) move a little. Adults cover themselves in a waxy, protective coating and remain stationary, so the small white or brown bumps may go unnoticed. Scales are most commonly found on the underside of leaves and on stems, but they can also be found on the upper leaf surface. While scales can eat a variety of houseplants, they are particularly fond of citrus trees, ivy, and figs.
Scale-infested leaves may yellow or fall off, and stems may die back. The bugs also leave a sticky substance on your plant known as honeydew. Aside from making a mess, the sweet residue can attract ants, and a black fungus known as sooty mold can grow on it. (This is not a good look.)
How to Control Scales
To suffocate crawlers, spray your plant with insecticidal soap ($10, The Home Depot) or neem oil ($11, The Home Depot). Because of their waxy covering, adults are more difficult to control. Scrape them off gently with your fingernail. Remove heavily-infested plant parts, such as older leaves, if possible. Examine your plant on a regular basis and scratch off any scales you find until the infestation is gone.
Mealybugs are sapsuckers with a waxy coating that produces dew, similar to scales. “Signs of a scale or mealybug infestation can include the presence of waxy deposits on the plant; of black sooty mold that grows on the honeydew produced by these insects, and (depending on how heavy the infestation is) sometimes yellowing and dying leaves, and distorted or stunted plant growth,” says Natalia von Ellenrieder of the California Department of Agriculture’s Plant Pest Diagnostic Branch. Female mealybugs make a white, cottony material in which to lay their eggs, which hatch into crawlers. Mealybugs are particularly damaging to Coleus, Hoya, Jade, Gardenia, and Poinsettia.
How to Control Mealybugs
To remove the mealybugs, use a cotton swab dipped in rubbing alcohol. To dislodge pests from larger, more robust plants, spray the leaves with a strong stream of water. For severe infestations, insecticidal soap and neem oil may be the best option.
3. Spider Mites
Spider mites are so small that you might not notice them. They appear as dark specks on leaves, but you’ll most likely notice their white silky webs in leaf axils or along veins first. The mites feed on the sap of the leaves, causing them to discolor and drop. Their favorite hosts include ivies, dracaenas, figs, hibiscus, and Scheffleras.
How to Control Spider Mites
Mite infestations are difficult to eradicate. If your plant is heavily infested, get rid of it as soon as possible before the pests spread. “For spider mites and scales, catching the problem early and inspecting plants regularly makes a big difference,” says Kelley Hamby, an entomology professor at the University of Maryland. “You can use some of the easier approaches of removing infested leaves, washing them off with soapy water, and crushing them.” Increasing humidity around plants may also aid in spider mite control.
These tiny, winged insects are powdery white in appearance. The immature stage does not move much, but when disturbed, the adults flutter around. Both stages suck plant sap, but the immature stage, feeding from the underside of leaves, causes the most damage. “Immature whiteflies look a bit like scale insects,” says Iles. Infested leaves turn yellow and die, and the plant frequently becomes stunted. Watch for them, especially on ivies, hibiscus, and poinsettias.
How to Control Whiteflies
Whiteflies can be removed with insecticidal soap or neem oil. “Be sure to apply to the underside of the leaves, where the whitefly immature stages will be,” Iles advises. “Treatment will probably need to be done weekly until you no longer see any immature or adult whiteflies.”
Another sap-sucking pest, aphids, produces sticky honeydew. They can attack a wide range of plants and are especially fond of tender, new growth, causing distortion and wilting. Because their life cycle is short (usually two to three weeks), populations can grow quickly.
How to Control Aphids
Most aphids can be removed with a strong spray of water. Take your plant outside to hose it down (if the weather isn’t too cold) or use your shower sprayer. Sprays containing insecticidal soap or neem oil are also effective.
6. Fungus Gnats
Although the adults of tiny fungus gnats are more of a nuisance than a pest, the immature stage (larvae) feeds on plant roots and can cause growth problems, particularly on young plants. “Fungus gnats are often a symptom of overwatering,” Hamby says.
How to Control Fungus Gnats
Allow the soil surface in pots to dry between waterings. Do not leave water in saucers. The larvae can be controlled by saturating the soil with the biological insecticide. Yellow sticky traps will aid in the capture of adults.
While any bug on your houseplants is undesirable, some pests are worse than others. The majority are all quite bothersome because they are little and slender, making them difficult to see, multiply quickly, and can crawl or fly, allowing them to easily infest your plant collection.’
Aphids are one of the most prevalent houseplant pests and may be a real pain in the neck. They thrive by sucking sap from the plant and using it to feed their colony, which produces honeydew secretions. If untreated, this might result in the growth of sooty mold. Aphids and other houseplant pests should be removed as soon as they are discovered.