Bringing houseplants indoors during the winter is a great way to beat the winter blues and keep your thumb green during the coldest months of the year. Unfortunately, most of the pests that endanger houseplants actually come into the home by hitchhiking on other plants.
Many pest problems start when a new plant is brought into the home. Maybe you were given a new plant as a gift. Or, perhaps some of your houseplants have been outdoors on the patio all summer.
Either way, it’s best to isolate any new plant from your other houseplants for at least 30 days. With a few smart precautions, you can prevent unwelcome houseplant pests from invading your home.
Common Houseplant Pests and How to Eradicate Them
Mealybugs are easy to miss until they become adults. In the adult stage of their lives, they produce a cottony white covering that makes them resemble tufts of white cotton.
They are very good at hiding, so they often go unnoticed until the plant starts to suffer. Mealybugs are sucking insects, which means they pierce the stems and leaves of your plants to suck out their rich sap, which usually stunts or kills the plant.
Often plants that are infested with mealybugs will be sticky from the honeydew the bugs excrete after they ingest the sap from the plant. This sap contains a lot of sugar, and it often leads to problems with sooty mold (a black, powdery fungus).
If the infestation is minimal, you can handpick the bugs to keep them under control. Once the outbreak gets out of control, you will need to call in the big guns. Two or three applications of pyrethrin at 10-day intervals should do the trick.
Check out our guide on how to get rid of white fuzzy bugs on your plants.
Aphids are another common houseplant pest that will suck the juice out of your plants and eventually kill them. These tiny insects can range in color from green to black, and sometimes they’re almost colorless.
Usually, they can be kept under control by spraying them off the plants with a steady stream of water. If that doesn’t work, try insecticidal soap or neem oil.
Here is our in-depth guide on how to identify, control and prevent aphids for more details.
3. Spider Mites
Spider mites pose a severe threat to your houseplants. If they go unnoticed, they will multiply fast and cause defoliation of your plant, and eventually, death. These microscopic pests are challenging to see with the naked eye so you may need to look for them with a magnifying glass.
Often, there will be tiny eggs, black fecal spots, and shed skins. You can also place a white sheet of paper under any discolored leaf, give it a gentle shake, and look for the tiny creatures moving around on the paper.
Other signs to look for include pinprick sized yellow spots on the undersides of the plant’s leaves. Often, spider mites will hitch a ride indoors on Christmas trees and other greenery.
They can be spread around on your hands as tools as you work with your plants, so wash everything carefully as you move from one plant to another, especially if you suspect issues with spider mites.
At the first sign of spider mites, begin spraying with insecticidal soap at seven-day intervals until the pests are gone.
Whiteflies are easy to identify because they look exactly like what their name implies. These tiny little white flies resemble gnats, and you’ll notice small swarms of them around your infested plants.
They are closely related to aphids and mealy bugs. They usually affect plants grown in greenhouses more than those grown in homes, but they can harm plants in the house, too.
Since these insects feed on the plant’s sap, an affected plant’s leaves will be limp and pale, often turning yellow and dropping off the plant. While these pests don’t usually kill the plant, they will reduce the plant’s health and vigor, stunting its growth.
To get rid of whiteflies, start by spraying them off your plants with a steady stream of water and follow up with at least three applications of insecticidal soap or neem oil at 5-day intervals.
Thrips are tiny, slender insects that are generally tan or dark brown in color. When they are immature, they will be either white, orange, or yellow. As adults, thrips can fly, jump great distances, and run fast, making them difficult to spot, especially without a magnifying glass.
Some types of thrips can’t survive indoors for very long, but others can thrive inside all year long. Leaves that have been damaged by thrips will have irregular silver splotches or streaks, and the plant’s flowers will also become distorted and streaked.
You may even notice black drops of excrement on the leaves of plants that are heavily infested. Hand picking, spraying with water, and two or three applications of permethrin or pyrethrin at 10-day intervals should get rid of them.
If you notice brown or gray bumps on your plant’s leaves, it could be scale insects. They are often found on the underside of the leaves and stems. They feed heavily by sucking out the plant’s sap with their needle-like mouths, which causes yellowing and stunts growth.
Two or three applications of pyrethrin, permethrin, or insecticidal soap at 10-day intervals will be required to get rid of a heavy infestation of scale insects. If there’s only a few, you might be able to rinse them off or pick them off individually.
We also have an in-depth guide to tiny white bugs if you have noticed some in your garden.
How to Prevent Houseplant Pests from Taking Over
Providing the right amount of light and water for each plant is crucial. Never overwater in the winter times. Overfertilizing can also be a problem. Fertilizing in winter encourages new growth, which is weak and delicate, making it especially susceptible to infestation.
Unless you have your houseplants under grow lights, it’s best to skip the fertilizer entirely in the winter time. There just isn’t enough light coming through the windows in the winter time to support vigorous new plant growth.
Those plants that are under lights can have a diluted solution of fertilizer in the winter but keep it to a minimum.
Be on the Look Out for these Houseplant Pests
The best thing you can do for your houseplants is to catch the pests early. Get into the habit of inspecting your plants every few days to look for signs of bugs. It’s much easier to get rid of a few houseplant pests on one plant than it is to get rid of a full-blown infestation on all of your plants.