Plant Problem Lab

Topic

Houseplant Pests

Use a magnifier on leaf undersides, stem joints, and new growth. Identify live pests or their distinctive traces before selecting treatment.

Useful checks and guides

Fungus gnatsLocate the source pot and treat the soil-dwelling larvae.Spider mitesClean, treat, and check leaf undersides through repeat cycles.ThripsDeal with hidden stages and protect emerging leaves.

Where to start

Separate an infested plant

Move it away from touching foliage. Inspect nearby plants too, treating those with the same pest.

Make new activity visible

Wipe off honeydew or rinse leaves, shielding the pot from excess wash water. Photograph damage and check for live pests after treatment; old scars will remain.

What it could be

Fungus gnats

What you may see: Small dark flies emerge from the potting mix; larvae live in the moist medium.

Next check: Use a sticky trap to locate the source pot. Control larvae as well as adults, while keeping moisture suitable for the plant.

Spider mites

What you may see: Fine pale stippling, tiny crawling dots, and sometimes delicate webbing.

Next check: Check undersides and tap a leaf over white paper. Rinse both leaf surfaces, then follow a mite treatment with repeat inspections.

Thrips

What you may see: Silver scars and black specks, often on distorted new leaves; slender insects may be visible.

Next check: Inspect open leaves and the outside of sheaths without forcing a new leaf apart. Treatment must account for stages missed by one application.

Mealybugs

What you may see: White waxy or cottony clusters in leaf joints, often with sticky honeydew.

Next check: Separate the plant and remove visible insects with a damp swab or cloth. For remaining insects, choose a product labeled for mealybugs on that houseplant and repeat as directed; inspect joints between treatments.

Scale

What you may see: Attached shell-like bumps on stems or leaf ribs; soft scales often leave honeydew.

Next check: Wipe or lift off accessible insects gently, preserving the stem surface. Use a labeled houseplant scale treatment for remaining insects and crawlers. Recheck stems because old shells can remain after insects die.

By plant

Houseplant Pests by plant

Choose your plant for more specific advice.

Browse plant library
Pothospothos brown spotsCheck leaf damage, pests, watering, and sun exposure.Open guideMonsteramonstera brown spotsUse texture and location to separate scorch, root stress, and pests.Open guideCalatheacalathea leaves curlingCheck timing, dry soil, humidity, pests, and heat exposure.Open guideCalatheacalathea brown tipsCheck mineral buildup, dry air, uneven moisture, and mites.Open guideAlocasiaalocasia yellow leavesSeparate normal leaf cycling from pests, cold, or watering swings.Open guideScheffleraschefflera dropping leavesConnect leaf drop with low light, wet soil, drafts, or scale.Open guide

Common questions

Can I use dish detergent instead of insecticidal soap?

Household detergent is not formulated or labeled for plant treatment and may damage leaves. Use an insecticidal soap labeled for the pest and plant, testing a small area first and following its directions.

When is discarding a plant reasonable?

If most growth is badly infested or repeated treatment cannot reach hidden colonies, discarding the plant can be simpler. Bag it before carrying it past other plants, then clean the pot and growing area.

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