Alocasia spider mites
Spider mites are almost invisible individually, so they are usually found by their damage: a fine pale speckling across an alocasia leaf that no watering problem produces. They breed fastest in warm dry air, which is why they arrive in winter.
What is specific to this plant
- Alocasia goes dormant. Losing leaves through autumn and winter, down to almost nothing, is normal behaviour and not a death, provided the corm stays firm.
- It is one of the most reliable spider mite magnets in the house. Check the undersides of the leaves before concluding anything about watering.
- Droplets on the leaf edges in the morning are guttation, which is the plant shedding excess water, and it is normal.
What it could be, and how to tell
These look alike in a photograph, so each one below lists what you would ALSO see if that is the cause. Work down the list and stop at the one where the other symptoms match too.
1. Mite stippling mistaken for a feeding problem
What else you would see
- fine pale flecking spread across the leaf rather than a defined patch
- the pattern read as pale mottling between the veins
- the undersides gritty or dusty when wiped with a white cloth
- the newest leaves affected as badly as the old ones
What to do
- Rinse the whole plant thoroughly, undersides included, and repeat every few days.
- Check it weekly from now on, since this plant reinfests faster than most.
- Raise the humidity around it, which mites do poorly in.
- If you choose a treatment product, follow its label exactly. The label is the legal instruction and it overrides anything written here.
2. Spider mites
What else you would see
- fine pale stippling or speckling across the leaf rather than solid patches
- very fine webbing where the leaf meets the stem
- a dusty look to the underside of the leaf, worst in warm dry air
What to do
- Isolate the plant from your others straight away, before anything else.
- Rinse the leaves thoroughly, undersides included, with a strong spray of water, and repeat every few days. Mites breed faster than a single treatment can keep up with.
- Raise the humidity around the plant. Mites thrive in warm dry air and struggle in humid air.
- If you choose to use a treatment product, follow the label on it exactly. The label is the legal instruction and it overrides anything written here.
3. Dry air letting the population explode
What else you would see
- onset in winter, once the heating is on
- the plant sits near a radiator or a vent
- other plants nearby starting to show the same stippling
What to do
- Raise the humidity around the plant and move it away from the heat source.
- Rinse the foliage regularly. Physical removal is what keeps the numbers down between anything else you do.
4. Brought in on a new plant
What else you would see
- a new plant, a cutting or a bunch of flowers arrived in the last few weeks
- the worst affected plant is the newest one
- damage spreading outward from one plant to its neighbours
What to do
- Isolate anything new for a few weeks before it joins your other plants.
- Treat every plant that was standing near the affected one, not only the one showing damage.
Common questions
How do I confirm spider mites rather than dust?
Hold white paper under a leaf and tap it firmly. Dust sits still. Mites walk. That takes ten seconds and settles it.
Do I have to throw the plant away?
Rarely. Mites are beatable with persistence: isolate, rinse thoroughly and repeatedly, and raise the humidity. What fails is treating once and assuming it worked.
Will they spread to my other plants?
Yes, readily, especially where leaves touch. Isolate the affected plant first and check its neighbours before you treat anything.
Is an alocasia poisonous to cats, dogs or children?
Alocasia contains calcium oxalate crystals and is widely listed as harmful to pets and children if chewed. We do not tell you that any plant is safe. If a pet or a child may have chewed any part of one, contact a vet, or Poison Control on 1-800-222-1222 in the US, immediately rather than waiting to see what happens.
Before you act on any of this
This is general plant care guidance for a plant, not advice about people or animals. We never tell you whether a plant is safe to eat or touch, and we never tell you a plant is safe for a child or a pet. If a child or animal may have eaten any part of a plant, contact Poison Control (US 1-800-222-1222) or a vet immediately rather than reading further.
Treatment advice here is deliberately category level. We do not give product names, mixing ratios or application intervals. Whatever the label on the product in your hand says is the instruction that counts, and following it is your responsibility.
Where this comes from
The general horticultural facts behind this differential come from published university extension and Royal Horticultural Society guidance. What is specific to this plant, and the order the causes are ranked in, is ours, and the methodology page says where that reasoning stops being reliable.
- Integrated Pest Management (I.P.M.) for Spider MitesClemson Cooperative Extension Home and Garden Information Center
- Spider MitesUC Statewide IPM Program, University of California
- Common Houseplant Insects and Related PestsClemson Cooperative Extension Home and Garden Information Center
- Diagnosing Houseplant Problems from Improper Environmental ConditionsIowa State University Extension and Outreach
- Glasshouse red spider miteRoyal Horticultural Society
Other alocasia problems
Not sure which one it is?
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