Tiny bugs in houseplant soil are most often fungus gnats. These are small, dark flies that hover near the pot and lay eggs in damp potting mix. Shore flies, springtails, and soil mites also live in wet soil. Mealybugs and spider mites feed on the plant itself and can end up on the soil. Most soil bugs point to soil that stays wet. Let the top of the soil dry between waterings. Catch adult gnats on yellow sticky traps. Treat the larvae with a biological soil drench.
Not sure which bug you have? Watch it. Small dark flies that rise from the pot when you water are fungus gnats or shore flies. Tiny pale bugs that jump are springtails. Slow, tan specks that crawl and never fly are soil mites. White cotton on the stems means mealybugs. Fine webbing and speckled leaves mean spider mites.
Common tiny bugs in houseplant soil
Colorado State University lists aphids, scale, mealybugs, thrips, spider mites, whiteflies, fungus gnats, and springtails among the most common houseplant pests. Six of them turn up in or near the soil. Each one needs a different fix, so name the bug before you treat it.
Fungus gnats
Fungus gnats are the most common bugs in houseplant soil. The adults are dark, delicate flies about 1/16 to 1/8 inch long, with long legs and long antennae. UC IPM describes them as weak fliers that stay near potted plants and run across the soil and leaves. They are drawn to light, so you may first see them on windows.
Females lay eggs in moist potting soil. The larvae have a shiny black head and a whitish, legless body. They feed on fungi and organic matter in the soil, and they also chew roots. The adults do not bite and do not harm plants. UC IPM notes that large numbers of larvae can damage roots and stunt growth, above all in seedlings and young plants. At 75°F (24°C), one generation takes about 17 days.
To confirm fungus gnats, place yellow sticky traps just above the soil. UC IPM also suggests a chunk of raw potato, cut side down, pressed into the soil. Check it after a few days for larvae. To kill the larvae, use a biological soil drench. UC IPM names beneficial nematodes (Steinernema feltiae) and Bti, a bacterium sold for fungus gnat larvae, as the top choices for homes. Bti does not persist indoors, so it may take repeat treatments about five days apart. Plants with heavy infestations may need repotting with fresh potting mix.
Shore flies
Shore flies look like fungus gnats at first glance. UMass Amherst points out the differences. Shore flies have stockier bodies and very short antennae. Each dark wing has five light-colored spots. They fly faster and stronger than fungus gnats.
Shore fly larvae feed on algae on wet soil and do not damage roots. The flies are a nuisance and a sign the soil stays too wet. Let the soil surface dry out between waterings and use yellow sticky traps to catch the adults.
Springtails
Springtails are tiny, wingless insects that jump when disturbed. University of Maine Extension puts them at 1/16 to 1/8 inch long. Most are dark, but some are white or pale. They feed on fungi, algae, and decaying organic matter in moist soil.
Clemson Extension notes that springtails are a sign of overwatering. They may chew seedlings or tender plant parts, but the damage tends to be minimal. Let the soil dry more between waterings, and their numbers drop. If you also see white fuzz on the soil, see white stuff in potting soil to tell mold from mineral salts.
Spider mites
Spider mites are not insects. They are tiny arachnids about 0.5 mm long, according to Colorado State University. The two-spotted spider mite (Tetranychus urticae) is a common houseplant pest. Mites start on the undersides of leaves and spread over the plant as numbers build. Low humidity and dust help them multiply.
Look for leaves with a speckled, faded look and fine webbing on leaves and stems. Iowa State University Extension suggests tapping a leaf over a sheet of white paper and watching for tiny specks that move.
Start with water. Spray the whole plant with a strong stream to knock mites off. UC Master Gardeners note that repeated water sprays help control spider mites. Then apply insecticidal soap or horticultural oil to all leaf surfaces, including the undersides. Soap kills only the pests it touches and stops working once it dries, so plan on more than one treatment. Watch plants such as monstera and peace lily in dry winter air.
Mealybugs
Mealybugs are soft, oval insects up to 1/10 inch long, covered in white, waxy fluff. Colorado State University says a single female can lay 200 to 600 eggs in a white, fluffy egg sac. They hide in leaf joints and along stems. They also produce sticky honeydew. Large populations can show up near the base of the stems and on the soil.
Dab each mealybug with a cotton swab dipped in rubbing alcohol. University of Maine Extension lists that method along with organic insecticidal soap, insecticidal soap, or neem oil. Check the plant every week. Eggs hidden in the stems can hatch after the first treatment.
Soil mites
Soil mites are tiny, pale to tan arachnids that crawl through moist potting mix and never fly. The most common are oribatid mites. Washington State University Extension says oribatid mites are thought to be scavengers that help break down decaying organic matter. They should not damage plants.
If the plant looks healthy and the specks stay in the soil, leave them alone. Removing the organic matter they feed on reduces their numbers. Pick up dead leaves, and let the soil dry more between waterings.
How to get rid of bugs in houseplant soil
Name the bug first, then follow these steps. Most infestations take more than one treatment.
Isolate the plant. Move it away from your other houseplants. UC Master Gardeners advise keeping a suspect plant apart until the pest is gone, which can take several weeks or more.
Let the soil dry out. UC IPM recommends letting the soil surface dry between waterings and giving the pot good drainage. This is the main fix for fungus gnats, shore flies, and springtails. Empty saucers of standing water.
Trap the adult flies. Place yellow sticky traps just above the soil in each pot. Colorado State notes that sticky traps help you monitor but will not end an infestation, since the larvae stay in the soil. Use them to track progress.
Treat the pest you found. For fungus gnat larvae, use beneficial nematodes or a Bti drench. For mealybugs, spider mites, and other soft-bodied pests on the leaves, spray insecticidal soap (also at Lowe’s) on every surface, including leaf undersides and stems. Wash sturdy plants such as pothos and snake plants under the sink sprayer or in the shower first. Follow the label for mixing and repeat timing.
Repot or discard plants with heavy infestations. When other steps fail, repotting into fresh mix can help. Use bagged, pasteurized potting mix, not garden soil. UC IPM notes that unpasteurized compost in a mix often carries fungus gnats. For a plant with a heavy infestation that is easy to replace, the Missouri Botanical Garden says tossing it is often the best choice.
How to prevent bugs in houseplant soil
Inspect plants before you buy. Check leaves, stems, soil, and the pot. Colorado State University Extension says scale, mealybugs, and whiteflies almost always arrive on plants that were just bought or received as gifts.
Quarantine new plants. Keep each new plant away from the rest for at least two to three weeks. Illinois Extension suggests 2 to 3 weeks, and Colorado State suggests at least three. Check it each week, above all under the leaves.
Water by need, not by schedule. Push a finger into the soil before you water. Fungus gnats, shore flies, and springtails all thrive in soil that stays wet.
Clear dead leaves. Fungus gnat larvae and soil mites feed on decaying plant matter. UC IPM notes that moist mulches and compost are favorite breeding spots for fungus gnats. Pick fallen leaves off the soil surface.
Wash plants now and then. The Missouri Botanical Garden suggests rinsing plants with lukewarm water every 6 months. It gives you a close look at each plant and knocks back pests before they build up.
Tiny bugs in houseplant soil FAQ
Are tiny bugs in houseplant soil harmful?
Some are and some are not. Adult fungus gnats do not harm plants, but UC IPM says large numbers of larvae can damage roots of seedlings and young plants. Shore flies and soil mites do not feed on healthy plants. Mealybugs and spider mites do damage plants.
What are the tiny white bugs in my plant soil?
Tiny white bugs that jump are springtails. Slow, pale specks that crawl are likely soil mites. White, cottony clumps on stems and near the soil line are mealybugs. Small white worms with shiny black heads are fungus gnat larvae.
Will letting the soil dry out kill fungus gnats?
It helps. UC IPM recommends letting the soil surface dry between waterings and improving drainage. Drier soil makes the pot less suited to egg laying and larvae. For a heavy infestation, add beneficial nematodes or a Bti drench.
Does insecticidal soap kill fungus gnats?
UC IPM does not list insecticidal soap for fungus gnats. It names Bti and Steinernema feltiae nematodes for the larvae in the soil. Insecticidal soap works on soft-bodied pests it touches, such as mealybugs and spider mites.
How long should I quarantine a new houseplant?
At least two to three weeks. Illinois Extension suggests 2 to 3 weeks, and Colorado State University Extension suggests at least three. Check the plant each week during that time.
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