(Pixabay / Manfred Richter)
How to Control the 5 Most Common Houseplant Pests
During the long, cold days of winter, houseplant pests often decide to throw a dinner party—and your houseplants are the main course.
If you’re suddenly seeing mealybugs on your pothos and scale on your ficus, you’re not alone. The combination of slow winter growth and soil that dries out slowly after watering invites these pests. Whatever the reason, it’s important to stop their invasion before it gets out of control.
Here are five common houseplant pests and how to control them using organic methods. It’s important to note that the goal is to control—not completely eradicate—them. Accepting their presence as part of indoor gardening makes it easier to manage them to tolerable levels.
1. Fungus Gnats
Fungus gnats look like fruit flies and hover around your face. However, it’s their larvae that damage your plants. Thriving in moist soil, they feed on decaying material and plant roots, which can cause wilting and root rot.
To control fungus gnats:
- Use yellow sticky traps to catch adults.
- Let the top 1–2 inches of soil dry out to kill larvae.
- Increase air circulation around plants.
- Repot the plant using fresh soil if necessary.
2. Mealybugs
These pests look like they’re covered in white cotton. They suck sap from leaves and excrete a sticky residue that attracts sooty mold and ants. Mealybugs are tough to remove because they lay eggs beneath their bodies for protection.
Mealybugs often hide in leaf joints and unfurling leaves. Larger infestations spread to stems and both sides of leaves, causing leaf loss and weakening the plant.
To control mealybugs:
- Spray with isopropyl alcohol or horticultural oil.
- Rinse pests off with water after spraying.
- Repeat treatment every 2–3 days for two weeks, then as needed.
3. Scale
Scale insects appear as brown, oval bumps on stems and the undersides of leaves. They feed on plant sap and produce a sticky substance that attracts mold. As a result, leaves yellow and fall off, and the plant becomes weakened.
To control scale:
- Remove them manually by rubbing them off or rinsing with water.
- Apply horticultural oil, alcohol spray, or insecticidal soap.
- Repeat treatment every 5–7 days for a month, then as needed.
4. Spider Mites
Spider mites are minuscule pests, visible only with a hand lens. They congregate on the undersides of leaves and produce fine webbing. By sucking plant juices, they cause yellow, spotted leaves that eventually drop. They thrive in hot, dry conditions.
To control spider mites:
- Rinse plants thoroughly with water.
- Increase humidity around the plant. Learn how to boost humidity.
- Use insecticidal soap or horticultural oil. (Only oil kills spider mite eggs.)
5. Thrips
Thrips are small, long-bodied insects with fringed wings that cause silver-colored, serpentine marks on leaves. They also leave tiny black droppings (frass) as they feed.
To control thrips:
- Increase humidity, as thrips prefer dry conditions.
- Rinse the plant thoroughly with water.
- Use blue sticky traps—they’re attracted to blue.
- Apply alcohol spray, insecticidal soap, or neem oil.
Julie Bawden-Davis is a garden writer and master gardener who has written for publications such as Organic Gardening, The American Gardener, Better Homes and Gardens, and The Los Angeles Times since 1985.
She is the author of 10 books, including Fairy Gardening, The Strawberry Story Series, and Indoor Gardening the Organic Way. She is also the founder of HealthyHouseplants.com.
Her backyard is a Certified Wildlife Habitat by the National Wildlife Federation.