Spider Mites: Spot Them and Kill Them
Published by Plantive · Updated September 29, 2026
Short answer
Isolate the plant now, because spider mites spread fast. Shower it thoroughly, then treat with an insecticidal soap or horticultural oil labeled for mites on indoor plants, repeating as the label directs to catch each new hatch.
Check these possible causes
- 1
Hot, dry air
most likelyHow to tell: Outbreak began in winter with heating on, or near a radiator or sunny window. Mites reproduce fastest in warm dry conditions.
What to do: Raise humidity above 50% and move the plant away from heat sources. Mites struggle in humid air.
- 2
A newly introduced plant
commonHow to tell: Symptoms appeared within a few weeks of bringing home a new plant or bringing plants in from outside.
What to do: Quarantine every new plant for two to three weeks, inspecting leaf undersides weekly before adding it to your collection.
- 3
Dusty, unwashed foliage
commonHow to tell: Leaves are visibly dusty. Mites shelter in dust and are harder to dislodge.
What to do: Wipe leaves monthly with a damp cloth and shower plants in the sink a few times a year.
- 4
Overcrowded plants with poor airflow
less commonHow to tell: Plants packed closely together; the infestation spreads from one to its neighbours within days.
What to do: Space plants so leaves do not touch, and improve ventilation.
Spider mites are the most damaging common houseplant pest, and the most easily missed. They are about 0.4 mm long, so you can see them, but only if you know to look. By the time webbing is obvious, the population is in the thousands.
Confirming it
The stippling. Look at the top surface of affected leaves. Spider mites feed by piercing individual cells and draining them, leaving a scatter of tiny pale dots. Early on it looks like fine dust or a faint speckling; later the whole leaf goes bronze or greyish and dull.
The paper test. The definitive check. Hold a sheet of white paper under a leaf and tap the leaf sharply two or three times. Mites fall off and show up as specks the size of ground pepper, moving slowly across the paper. Dust does not move.
The webbing. Fine silk strands where the leaf meets the stem, between leaves, or across new growth. This means an advanced infestation, so act immediately.
Where to look: undersides of leaves, leaf joints, and new growth. Use your phone camera zoomed in if your eyes will not resolve them.
Act on isolation first
Before you treat anything, move the plant away from every other plant. Spider mites travel on air currents, on your sleeves, and along touching leaves. A single infested plant in a collection becomes five infested plants in a fortnight.
Check the neighbours it was touching too. They are probably already carrying mites.
The treatment
Three weeks, no shortcuts. The reason infestations come back is almost always stopping early.
Step 1: physical removal
Take the plant to a shower or sink and rinse it thoroughly, paying particular attention to leaf undersides and joints. Lukewarm water, moderate pressure. This removes the bulk of the adult population immediately and is the highest-value single action you can take.
For a large plant, wipe every leaf on both sides with a damp cloth.
Step 2: spray, then repeat on the label’s schedule
Choose one:
- Insecticidal soap: gentle and widely available. It works on contact, so it must reach the mites.
- Horticultural or neem oil: smothers mites and eggs it covers. Buy a ready-to-use or concentrate product labeled for mites on indoor plants and mix only as the label says.
Whichever you choose, check that the label covers spider mites, indoor use and your plant, and test it on one leaf a day or two before treating the whole plant. Homemade sprays such as dish-soap or rubbing-alcohol mixes are not a substitute: their strength is unregulated and some plants are damaged by them.
Spray until the leaves are dripping, especially the undersides, plus the stems and the soil surface. Anything you miss is where the survivors will be.
Repeat the treatment on the interval the label gives, for as long as it allows. This is the part that matters. Contact sprays miss many eggs, and new mites keep hatching, so a single spray almost never ends an infestation. Keep checking with the paper test for a few weeks after the last treatment.
Spray in the evening or out of direct sun; oil and soap on sunlit leaves can scorch them.
Step 3: change the conditions
Spider mites explode in hot, dry air, which is exactly what a heated home in winter provides.
- Raise humidity above 50% with a humidifier
- Move the plant away from radiators and heating vents
- Space plants so their leaves do not touch
- Wipe leaves monthly, since dust is shelter
What not to bother with
- Misting alone. Helps prevent, does not cure.
- A single spray. Kills the adults you hit and nothing else. The eggs hatch a week later and you are back where you started.
- Systemic granules for indoor plants. Overkill for most homes, and many are not labelled for indoor use.
Preventing the next one
- Quarantine new plants for two to three weeks, checking undersides weekly. This is where most infestations come from.
- Inspect when you water. Turn over two or three leaves each time. Thirty seconds a week catches problems while they are small.
- Keep humidity up in winter. The single biggest environmental lever.
- Check plants coming in from outdoors in autumn especially carefully.
If leaves are yellowing and you are not sure whether mites are the cause, work through the other possibilities in why plant leaves turn yellow. Stippled yellowing looks quite different from the even yellowing of overwatering.
Frequently asked questions
How do I know it is spider mites and not something else?
Two checks confirm it. First, look for fine stippling, meaning tiny pale dots across the leaf surface where mites have pierced individual cells. Second, hold a sheet of white paper under a leaf and tap the leaf sharply: mites fall off and appear as slow-moving specks the size of a grain of pepper. Visible webbing between stems and leaf joints confirms an advanced infestation.
How long does it take to get rid of spider mites?
Usually several weeks. Mites develop quickly in warm, dry rooms and contact sprays miss many eggs, so plan on repeat treatments at the interval your product label gives and keep checking afterwards. Stopping when the plant looks better is the most common reason infestations return.
Does misting prevent spider mites?
It helps slightly but is not a treatment. Spider mites thrive in dry air, so raising ambient humidity above 50% genuinely makes conditions less favourable, but misting only lifts humidity for a few minutes at a time. A humidifier is far more effective. Once mites are established, humidity alone will not clear them.
Should I throw the plant away?
Not usually. Most infestations are treatable with several weeks of consistent effort. Consider discarding only when the plant is severely damaged, heavily webbed across most of its foliage, and sitting near a large collection you would risk infecting. If you do discard it, bag the plant before carrying it through the house so mites do not brush off onto others.
Other problems to rule out
White cottony clusters on leaves and stems
Isolate the plant, remove the mealybugs you can see by hand, rinse it and prune out heavily infested stems. If you need a product, choose one labeled for mealybugs and indoor use and follow the label. Keep inspecting weekly, because eggs and hidden insects often survive the first round.
lowTiny black flies around plant soil
Confirm the flies are fungus gnats, then address the damp potting mix where larvae develop. Use yellow sticky traps to monitor adults. If needed, choose a larval treatment labeled for fungus gnats on indoor potted plants, such as an appropriate Bti product.
lowBrown, crispy leaf tips
Brown tips are usually low humidity or mineral build-up from tap water, not thirst. Switch to filtered water, raise humidity, and flush the pot to leach out salts.
Published July 24, 2026 · Updated September 29, 2026