Spider Mites on Houseplants: Find Them and Stop the Damage
Look under a speckled leaf before changing the watering routine. Spider mites can leave foliage pale, dusty-looking, or bronze, and a heavy infestation produces fine webbing around leaves and stems. You may find live mites before any webbing is obvious.
Find the mites, not just the damaged leaf
Hold white paper below an affected leaf and tap it. Watch for tiny moving dots, then inspect the underside with a hand lens, especially beside veins. Spider mites can be yellowish, green, brown, or red; their color alone is not the deciding clue. Maryland Extension's mite guide illustrates the mites, feeding marks, and paper test.
A few strands from an ordinary spider are different from fine webbing spread across stippled foliage. Silver scars with slender, rice-shaped insects and black deposits suggest thrips. If you see only dry tips and no feeding marks or pests, use the brown-tip checks.
Separate the plant and wash the foliage
Move the infested plant away from neighboring foliage. Inspect the plants that were touching it and treat any confirmed infestations together. Wash your hands and tools afterward so mites are not carried back to clean plants.
- Bag and remove leaves that are heavily webbed and badly damaged. Keep usable green foliage.
- Take a small plant to a sink or shower. Support delicate leaves and rinse both surfaces, directing water under the leaves and along the stems.
- For large leaves, wipe them with a damp cloth, changing to a clean section frequently. Keep contaminated wipes away from other plants.
- Let the plant drain. Shield already-wet potting mix while washing so repeated leaf cleaning does not become repeated soil soaking.
Colorado State Extension recommends washing or wiping houseplants and removing heavily infested tissue. A rinse removes many mites but can miss eggs and sheltered individuals.
If live mites remain, choose a mite treatment
An insecticidal soap or horticultural oil labeled for spider mites on indoor plants is an option after washing. Check that the product permits use on your plant. These contact treatments need to reach mites, including those underneath the leaves; spraying only the upper surface misses much of the population.
Use the label's dilution, coverage, repeat interval, and temperature restrictions. Test a small area first if the plant's sensitivity is unknown. A plant that is severely wilted or heat-stressed is more prone to spray injury. Household dish detergent is not interchangeable with insecticidal soap. Colorado State's soap guide explains the difference and the risk of leaf damage.
Spider mites are arachnids, so a product sold for insects is not automatically effective against them. Check that mites are on the label instead of choosing a generic systemic insecticide.
Follow through after the first clean leaves
Inspect the undersides and repeat the paper test every few days during an active outbreak. Record when you washed or treated the plant. Repeat washing as needed and any pesticide application only at the permitted interval. Eggs or missed mites can restart the population; one apparently clean day is not a reliable endpoint.
Keep checking neighboring plants. Keep it separate through the treatment course, then look for several weekly inspections with no live mites, fresh webbing, or new feeding damage before returning it to the group. Old stippling remains, so use live mites and fresh damage to judge progress.
Move mite-prone plants away from hot, dry vents and prevent repeated drought. Improving the growing conditions helps the plant tolerate damage, but humidity changes alone will not remove an established infestation. If a plant is severely damaged and continues to seed nearby plants despite treatment, bagging and discarding it is a reasonable endpoint.
