Spider Mites on Houseplants: Signs, Causes, and How to Get Rid of Them

Spider mites aren’t insects. They’re tiny arachnids, and most people only notice them once leaves look faded and fine webbing appears between the stems. They love warm, dry air, which is why a heated apartment in winter can turn a few mites into a full-blown infestation.

This guide uses integrated pest management (IPM): confirm the pest, fix the conditions that favor it, knock the population down physically, bring in predators, and keep pesticides as the last step.

How to identify spider mites

Adult spider mites are less than 1/20 inch long, with eight legs, an oval body, and two eyespots. You’ll need magnification to see them clearly, and they live in colonies on leaf undersides, often with webbing (UC IPM). The RHS lists the two-spotted spider mite (Tetranychus urticae) among the main sap-feeding pests of houseplants.

Despite the common name “red spider mite,” they’re usually yellowish-green with dark markings. They only turn reddish-orange in fall or when a plant is so damaged it can no longer support them (RHS).

Signs to look for:

• Stippling: tiny pale dots on the upper leaf surface (UC IPM, RHS).
• A faded, washed-out look to the leaves, which Clemson HGIC describes as the result of speckling.
• Silky webbing on leaf undersides, between leaf stalks, and at shoot tips.
• Yellowing, reddening, and leaf drop in severe infestations (UC IPM).

Where to look

• Leaf undersides, especially along veins and near the stem,
• shoot tips and young leaves, where webbing often shows first,
• plants next to a radiator or heating vent or on a hot, sunny sill,
• spots where leaves touch a neighboring plant.

A 10x hand lens and a flashlight make a big difference. Mites are small enough to miss with the naked eye even on a heavily infested leaf.

The white paper test

Tap a leaf over a sheet of white paper and look closely. Specks that start moving are mites. UC IPM stresses confirming that mites are actually present before you treat, because stippling can stay on leaves long after the mites are gone.

Why spider mites multiply so fast

Spider mites thrive in hot, dusty conditions and on water-stressed plants (UC IPM). Their development speeds up sharply with temperature:

Temperature	Time for one generation (RHS)
50°F (10°C)	about 55 days
70°F (21°C)	about 12 days

UC IPM notes that under favorable temperatures a generation can be completed in less than a week. Indoors with the heat on, a few weeks of not looking closely can be enough for visible damage.

Step 1: Isolate the plant

Move the infested plant away from your other houseplants. The RHS recommends separating plants with sap-feeding pests from unaffected ones to minimize spread. Then check the neighbors, starting with plants near heat sources.

Step 2: Water and better conditions

This is the most effective low-cost step for spider mites.

• Hose them off. Clemson HGIC recommends spraying sturdy plants forcefully with water, including leaf undersides, to dislodge mites and break up webs. UC IPM lists regular water sprays as a core non-chemical method. Repeat weekly for several weeks.
• Wipe large leaves. On big smooth leaves like a rubber plant or an Alocasia ‘Polly’, wipe both surfaces with a damp cloth. Rinse the cloth after each leaf.
• Raise the humidity. The RHS lists keeping humidity high as a preventive measure. See our houseplant humidity guide for practical ways to do it.
• Avoid drought stress. UC IPM notes that adequate watering reduces plant stress. Our guide on how to water houseplants covers the basics.
• Keep dust down. UC IPM includes dust control among its cultural methods.
• Remove heavily damaged leaves and bag them before throwing them out.

Step 3: Predatory mites

Spider mites have effective natural enemies. The RHS calls Phytoseiulus persimilis the most commonly used biological control for spider mites. It’s an orange-red, pear-shaped predatory mite about 0.5 mm long that hunts every life stage of spider mites. UC IPM also mentions western predatory mites alongside Phytoseiulus.

Keep in mind:

• Temperature matters. The RHS notes that Phytoseiulus needs suitable temperatures to establish. Follow the supplier’s release instructions.
• No pesticides. Biological controls are susceptible to pesticides (RHS), and UC IPM notes predators do their job where pesticides aren’t used.
• Start early. Predators work best on a developing infestation. Hose off a heavily infested plant first.

Step 4: Sprays

UC IPM recommends insecticidal soap and horticultural oils as selective treatments, applied with thorough coverage of leaf undersides. Clemson HGIC mentions insecticidal soap or neem oil and notes that weekly sprays for several weeks may be needed. Both act on contact only.

General rules:

• Spider mites are not insects. A product labeled only for insects may not work on them. Check that the label lists mites.
• Use only products registered in your state and labeled for houseplants or indoor ornamentals.
• Take the rate and repeat interval from the label only.
• Test on one leaf first and wait a day or two for any leaf burn.
• Don’t spray in direct sun, and keep kids and pets away during application.

Treatment timeline

When	What to do
Day 0	isolate, hose off thoroughly, remove the worst leaves
Week 1	second rinse or first spray per the label; or release predators
Weekly	white paper test on old and new leaves
Following weeks	continue until several checks in a row come back clean

Stippled leaves stay stippled. Judge success by clean new growth and an empty sheet of paper.

When to throw the plant out

Not every plant is worth saving. For severe infestations, the RHS recommends removing badly affected plants so mites don’t spread. Consider it if most leaves are faded and webbed, if the plant is common and easy to replace while a more valuable collection sits nearby, or if the mites keep coming back after weeks of consistent treatment.

With a rare plant, you can try to rescue a clean top or cutting. Rinse it carefully, inspect it under a lens, and keep it in quarantine. Bag and discard the rest, then wash the pot.

Spider mites or thrips?

Both cause pale spots on leaves, but they’re easy to tell apart:

Sign	Spider mites	Thrips
Damage	fine stippling, faded leaves	silvery patches with black specks
Webbing	yes, in heavier infestations	no
Pest shape	oval, 8 legs	slender, fringed wings
Flies	no	adults do

If it looks like thrips, head to our thrips guide.

Common mistakes

• One rinse and done. Some mites and eggs survive, and numbers rebound.
• Spraying only the top of the leaf. Mites live mostly underneath.
• Leaving the plant over the radiator. If the hot, dry conditions don’t change, the mites return.
• Predators plus pesticides. A spray kills the predatory mites too.

Prevention

• Quarantine new plants. Clemson HGIC recommends six weeks of isolation with weekly inspections under magnification.
• Wash smooth-leaved plants every two to three weeks, as Clemson HGIC suggests.
• Keep plants out of direct streams of warm air.
• Check leaf undersides every time you water, especially during heating season.
• Clear out dead leaves and debris where mites can shelter (RHS).