Spider mites are one of the most damaging houseplant pests precisely because they’re so easy to miss at first. By the time you notice speckled leaves or fine webbing, they’ve usually been feeding for weeks. Acting fast — and knowing what actually kills them — makes the difference between saving a plant and losing it.

What spider mites are

Spider mites aren’t insects. They’re arachnids, related to spiders and ticks, which is part of why they’re harder to deal with than something like fungus gnats or aphids — a lot of common insecticides don’t touch them. They’re also tiny, often under half a millimeter, so you’re more likely to spot the damage they cause than the mites themselves.

How to identify them

Stippled or speckled leaves are the first sign most people notice. Spider mites feed by piercing individual plant cells and sucking out the contents, which leaves behind tiny pale or yellow specks across the leaf surface. From a distance it can look like dust or a light case of underwatering, but up close the speckling has a fine, uniform, sandpaper-like texture.

Fine webbing is the giveaway once an infestation is established. It’s much finer than a spider’s web — closer to a dusty film stretched between leaves, along stems, or in the crook where a leaf meets the stem. If you see webbing, the infestation is no longer minor.

A dry, dusty look to the foliage overall, sometimes with a faint bronze or gray cast on leaves that should be glossy green.

To confirm, hold a sheet of white paper under a suspect leaf and tap the leaf sharply. If tiny specks fall onto the paper and start crawling, that’s spider mites. A magnifying glass or your phone camera zoomed in will also show the mites themselves — tiny oval specks, often reddish, tan, or greenish depending on the species.

Why they show up

Spider mites thrive in warm, dry conditions. Low humidity speeds up their reproduction dramatically, which is why infestations spike in winter when indoor heating dries out the air, and why they’re often worse on plants kept near heat vents or in consistently dry rooms. See how to increase humidity for houseplants for ways to fix the underlying condition rather than just treating the symptom.

Dust on leaves also seems to encourage them, so a plant that hasn’t been cleaned in a while is more hospitable than one with dust wiped off regularly — see how to clean houseplant leaves. Overly dry soil and a generally stressed plant are more vulnerable too, since a stressed plant has less capacity to recover from feeding damage. Spider mites also spread easily between plants that are placed close together, so one infested plant on a crowded shelf can seed an infestation across the whole group within days.

How to get rid of them

Isolate the plant immediately. Move it away from your other houseplants the moment you suspect spider mites. They don’t fly, but they crawl readily between touching leaves and can also drift short distances on air currents, so distance matters.

Rinse the plant off. A strong spray in the shower or sink, focusing on the undersides of leaves where mites concentrate, physically knocks a large portion of the population off the plant. This alone won’t clear an infestation, but it reduces the numbers before you treat.

Treat with insecticidal soap or neem oil. Both work by disrupting the mites’ outer coating on contact, and both need to actually touch the mites to work — there’s no systemic effect. Spray thoroughly, especially the undersides of leaves and along stems, until the plant is dripping. A horticultural miticide is worth reaching for if soap and neem aren’t cutting it, since some spider mite populations are more tolerant of the milder treatments.

Repeat every 5-7 days for at least three rounds. This is the step people skip, and it’s why mite treatments so often seem to fail. Sprays kill active mites but not eggs, and eggs hatch on a roughly weekly cycle. One treatment knocks back the population; skipping the follow-ups lets the next generation rebuild it right back up.

Increase humidity around the plant during and after treatment. Mites reproduce far more slowly in humid air, so raising humidity works alongside the sprays rather than replacing them.

How to prevent them coming back

Keep humidity reasonable, especially in winter, and keep an eye on plants that sit near heating vents or in south-facing windows where the air runs dry. Wipe leaves down periodically to clear dust, and inspect new plants closely — including the undersides of leaves — before placing them near your existing collection. Spider mites are one of the more common hitchhikers on plants brought home from a nursery, alongside the other usual suspects covered in common houseplant pests and how to get rid of them.

Spacing plants out a bit, rather than crowding them leaf to leaf, also slows the spread if mites do show up, giving you a better chance of catching and isolating one infested plant before it becomes three.

When to give up on a plant

If a plant is heavily webbed, most of its leaves are bleached or bronzed, and new growth is already stunted or deformed, the damage is often too extensive to reverse even if you clear the mites. In that case, it’s reasonable to propagate any healthy cuttings you can salvage — see how to propagate houseplants from cuttings — and discard the rest rather than sinking weeks into treating a plant that won’t recover its appearance anyway. A plant with only light stippling and no webbing is almost always worth treating through; one that’s already collapsing under a heavy infestation usually isn’t.