Plant care guide

Calathea Spider Mites: Why They're Prone and How to Treat

Updated

Why does my Calathea have spider mites?

Calatheas are prone to spider mites mainly because the warm, dry air of a heated home suits the mites and stresses the plant. Look for fine pale speckling, yellowing or silvery leaves and webbing, with tiny moving dots on the purple undersides.

What to do first

Isolate the plant, rinse or wipe both leaf surfaces, then raise humidity near the leaves. If mites return, use an insecticidal soap or horticultural oil labelled for houseplants, test it on one leaf first, and repeat weekly.

Finding mites on a calathea is upsetting, and it often happens just as the plant was settling in. The usual reason is the room, not the plant: calatheas are often kept in the dry, warm air mites like best. Fix those conditions and treatment works far better.

Most plants sold as calathea are now Goeppertia. NC State Extension’s Goeppertia profile lists spider mites with aphids, scale and mealybugs as the genus’s pests. The RHS calathea guide names red spider mite.

Why Calatheas Are Prone

The mites thrive where calatheas struggle.

  • Dry air. The RHS indoor sap-feeders page says red spider mite thrives in warm, dry conditions. NC State asks for 60% humidity for G. makoyana. Iowa State Extension notes homes often fall to 10–20 percent in winter.
  • Water stress. UC IPM’s spider mite notes say populations surge on plants under water stress and in hot, dusty conditions. A calathea whose mix dries hard between waterings fits that.
  • Dust. NC State notes dust collects on calathea leaves and recommends wiping it off with a damp cloth.
  • Year-round indoors. Clemson Extension’s houseplant pests factsheet says mites are more of a problem on houseplants that stay indoors all year.

University of Maryland Extension’s thrips page adds that high humidity may discourage spider mites on indoor plants.

Confirm It Is Mites

The RHS describes fine pale mottling on the upper surface, with speckled, yellowing or silvery leaves and fine webbing. UC IPM says leaves later turn yellowish or reddish and drop.

  1. Turn a few leaves over. The purple undersides of many calatheas make mites hard to see, so use a hand lens.
  2. Look for tiny moving dots, eggs and silk along the veins.
  3. Hold white paper under a leaf and tap it. Specks that crawl are mites.

UC IPM notes you usually see damage before the mites. Brown, crisp edges without speckling point to dry air or water instead; see our calathea curling leaves guide.

Treat Without Damaging Thin Leaves

NC State describes G. makoyana leaves as papery thin. Treat gently and check the plant after each step.

  1. Isolate the plant. Move it away from other houseplants until it stays clean.
  2. Rinse both leaf surfaces. UC IPM suggests frequent washing of leaf surfaces and reducing dust. Clemson recommends forceful water sprays for sturdy plants; for a calathea, use a lukewarm shower and support each leaf. Let foliage dry, because UC IPM warns prolonged wetness may favour disease.
  3. Wipe each leaf. A damp, soft cloth removes mites and dust from both sides.
  4. Cut off badly damaged leaves. UC IPM advises disposing of infested plant parts.
  5. Use soap or oil as the next step. UC IPM lists horticultural oil or insecticidal soap labelled for your plant as a last resort. Coverage of the undersides matters.

Spray safely:

  • Test first. UConn’s insecticidal soap factsheet says to spot-treat and wait at least 24 hours for spotting, burned tips or scorch.
  • Water the plant first. UC IPM says not to use soaps or oils on water-stressed plants or above 32 °C (90 °F).
  • Mix with soft water. UConn warns soap mixed in hard water may be less effective and more toxic to plants. Rainwater or distilled water also suits calatheas.
  • Repeat. Clemson says it is often necessary to spray once a week for several weeks.

Our spider mite guide and pest treatment guide cover the full treatment ladder.

Keep Them From Coming Back

  • Raise humidity near the leaves with a humidifier, grouped plants or a pebble tray, as Iowa State suggests.
  • Keep the mix evenly moist, not dry, through the growing season.
  • Wipe the leaves regularly; it doubles as an inspection.
  • Clemson advises isolating new plants for six weeks.

Damaged speckling will not fade. Judge success by new leaves that open clean. The calathea hub lists our other guides.

Other calathea problems we cover: drooping, water quality sensitivity, leaf movement, sunburn treatment, root rot.

References

How this guide was put together: NC State Extension, RHS, UC IPM, Clemson Cooperative Extension, University of Maryland Extension, UConn and Iowa State University Extension guidance.

Other Calathea problems

Related plant care guides

Knowledge record: pg-calathea--spider-mites