Common Pests on Indoor Plants (and How to Treat Them Without Chemicals)

Indoor plants get fewer pests than outdoor ones, but not zero — and the pests that do find their way in thrive in exactly the conditions a heated home provides: dry air, no predators, and no weather to knock them back. Here’s how to identify what’s actually on your plant and deal with it without reaching for a chemical spray indoors.

Identify what you’re actually looking at

What you see	Likely pest
Fine webbing, pale speckled leaves	Spider mites
Tiny flies around the soil surface	Fungus gnats
Clusters of small pale-green or black bugs on new growth	Aphids
Tiny white insects that fly up when disturbed	Whitefly
White, cottony fuzz in leaf joints	Mealybugs
Small brown bumps that don't move on stems or leaf undersides	Scale

Spider mites

The most common indoor pest by a wide margin, because they specifically like the warm, dry conditions central heating creates. They’re covered in more detail in why indoor basil is dying, since basil is especially prone to them, but they affect nearly any indoor plant.

Identify: fine speckling on leaves (stippling), and in advanced cases, fine webbing between stems. Tap a leaf over white paper — moving specks confirm it.

Treat: rinse the whole plant thoroughly, especially leaf undersides, in a sink or shower. Increase humidity around the plant afterward. Repeat every few days for two weeks — mite eggs survive a single treatment.

Fungus gnats

More annoying than damaging in small numbers, but a sign that something about your watering routine needs adjusting.

Identify: small dark flies, roughly the size of a fruit fly, hovering near the soil surface or appearing when you water.

Treat: let the top 2–3cm of soil dry out fully between waterings — gnats breed in the top layer of consistently damp soil, and interrupting that is usually enough on its own. A thin layer of sand on top of the soil also helps, since gnats can’t lay eggs through it. A densely sown microgreen tray is especially prone to this, since it’s kept damp and covered by design — see microgreens troubleshooting for telling that dampness-loving fuzz apart from actual mould.

Aphids

Common on new, soft growth — the tender tips of a fast-growing plant are exactly what they’re after.

Identify: small clusters of soft-bodied insects, usually pale green or black, clustered on new leaves and stem tips. Look for a sticky residue on nearby leaves too — that’s aphid honeydew, and it’s often the first thing people notice before spotting the insects themselves.

Treat: a firm spray of plain water knocks most of them off; follow with a wipe-down of affected leaves. For a heavier infestation, a diluted insecticidal soap spray (widely available, safe for edible plants when used as directed) handles what water alone doesn’t.

Whitefly

Less common indoors than the others, but persistent once established.

Identify: tiny white, moth-like insects that scatter into the air when you disturb the plant, then resettle on leaf undersides.

Treat: yellow sticky traps placed near the plant catch adults effectively. Combine with the same insecticidal soap approach used for aphids for anything already on the leaves.

Mealybugs

Slow-moving and easy to miss until the infestation is well established.

Identify: small, white, cottony-looking clusters, usually tucked into leaf joints or along stems rather than spread across leaf surfaces.

Treat: dab individual mealybugs with a cotton swab dipped in isopropyl alcohol — this kills them on contact and is effective for light infestations. Follow up with insecticidal soap for anything the swab missed.

Scale

The pest most often mistaken for a plant disease or a natural growth, because it doesn’t move.

Identify: small, brown, dome-shaped bumps on stems or leaf undersides that don’t move when touched — that stillness is the giveaway that it’s an insect (with a protective shell) and not a leaf spot.

Treat: scrape off visible scale gently with a fingernail or soft toothbrush, then treat the area with insecticidal soap or a light horticultural oil to catch anything too small to see yet.

Why chemical sprays are usually the wrong first move indoors

Outdoor pesticide use benefits from open air and distance from where people eat and breathe. Indoors, a sprayed plant sits in the same room you’re in — often the kitchen, next to food. The methods above (rinsing, physical removal, isolation, insecticidal soap used as directed) handle the vast majority of indoor infestations without introducing a stronger chemical into your living space than necessary.

Prevention beats treatment

• Inspect new plants before they join the others. Anything brought home from a shop is the single most common source of a new infestation.
• Keep humidity moderate. Very dry air favors spider mites specifically; moderate, consistent humidity makes your whole collection less hospitable to them.
• Don’t overwater. Consistently wet soil is what draws fungus gnats in the first place — the same watering discipline covered throughout this site for plant health also happens to be pest prevention. See how to water indoor herbs and vegetables for the finger test and when a moisture meter actually helps.
• Check plants regularly, not just when something looks obviously wrong. Every pest on this page is far easier to deal with caught early than caught established.