Spider Mites on Houseplants
Spider mites are tiny plant pests, closely related to spiders, that feed on the leaves of nearly all houseplants. They're hard to see with the naked eye, but the damage they do is distinctive — and they love the hot, dry conditions common in homes.
What spider mites are
Spider mites are very tiny pests (about 1/50th of an inch) related to spiders. The most common houseplant species is the two-spotted spider mite. They have piercing mouthparts and suck sap out of leaf cells, and they can be a problem indoors year-round. Certain plants — like ivy and dracaena — are especially susceptible.
The signs
- Fine white speckling or stippling on the leaves where mites have sucked out the cell contents.
- Very fine webbing over leaves and stems when populations are high — the easiest way to tell spider mites apart from other small pests.
- Heavy feeding turns foliage yellowish, then tan or brown, and can cause leaf drop.
- To check, hold a piece of white paper under a stem and tap it — mites show up as tiny, slow-moving specks.
Why they appear: hot, dry air favors spider mites. They're often worse in winter when indoor air is dry, and they're frequently introduced on infested new plants.
How to control them
1. Wash the plant with a strong spray of water, making sure to cover the undersides of the leaves, to knock mites off. Repeat over a couple of weeks. 2. Raise humidity around the plant — mites thrive in dry conditions. 3. Use insecticidal soap or a houseplant spray labeled for spider mites and houseplants, covering the undersides of leaves well and following label directions. Repeat as needed, since mites rebound quickly. 4. Quarantine new plants and discard heavily infested plants you don't want to save, so they don't spread.
Good plant health and regular leaf inspection go a long way, and staying on top of the population (repeated washes and treatments) is what wins.
Why they spread — and how to stop it
Spider mites spread easily from one plant to another. A single heavily infested plant can seed the rest of your collection, so it's worth treating all the susceptible plants around the same time and checking any new plant carefully before you bring it in. Because hot, dry conditions favor mites, keeping plants well watered (so they aren't drought-stressed) and the surrounding air less dry makes a flare-up less likely. Wiping dust off the leaves also helps, since dusty, dry foliage is where mites thrive.
Prevention is easier than a cure: inspect the undersides of leaves regularly with your eyes — or the white-paper tap test — so you catch mites early, keep plants well watered and the air reasonably humid, and quarantine any new plant before it joins your collection. Early detection and a quick wash are the fastest way to stop a small problem from becoming an infestation.
Related plants
- English ivy — very susceptible to spider mites
- Dracaena — a common target
- Calathea — can be hit in dry conditions