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Why Are My Houseplant's Leaves Sticky?

Last reviewed: October 2026

Quick answer

Sticky leaves are usually honeydew, a sugary substance left by insects that suck sap. Scale, mealybugs and aphids are the common sources. Over time the sticky film can turn black with sooty mold, so find and treat the insects.[3][1]

Causes and how to tell them apart

  1. Scale insects[1][2]

    How to tell: Look for small bumps or scales clustered or lined up along stems and leaf veins. The bumps are hard shell-like coverings, not part of the plant.

  2. Mealybugs[1][3]

    How to tell: Look for white, cottony insects in leaf axils and on the undersides of leaves.

  3. Aphids[1][3]

    How to tell: Look for small, soft-bodied insects, often green, brown or reddish, clustered on new growth and under leaves.

  4. Sooty mold on old honeydew[1]

    How to tell: If the sticky film has turned black, sooty mold is growing on it. It means honeydew has been there for a while, so the insects are still the root problem.

What to do, step by step

  1. Check stems, leaf axils and the undersides of leaves with good light to see which pest it is.[1][3]
  2. Wipe the sticky leaves with a damp cloth, or rinse the foliage thoroughly in a shower or outdoors.[3][1]
  3. For small infestations, scrape off scale and dab pests with a cotton swab dipped in rubbing alcohol.[2][1]
  4. If pests remain, use an insecticide such as insecticidal soap. Repeat on a schedule: scale needs a repeat every 7 to 10 days, and mealybugs weekly for 4 to 6 weeks. Check the label lists your plant.[2][1]
  5. If a plant is heavily infested with scale, it may be best to discard it so the insects do not spread to your other houseplants.[2]

How to prevent it

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Frequently asked questions

Is the sticky stuff on my plant leaves harmful?

The sticky film is honeydew. It is a sign that insects are feeding on the plant, and over time it can turn black with sooty mold.[1][3]

How do I get rid of sticky residue on plant leaves?

Wipe it off with a damp cloth or rinse the leaves. Then treat the insects making it, or the film will come back.[3]

Why are there sticky leaves and small bumps on my plant stems?

Those bumps are likely scale insects. They give off sweet, sticky honeydew as they feed.[2]

Related plant problems

Sources

  1. Iowa State University Extension: Diagnosing Houseplant Problems Caused by Insect Pests
  2. Iowa State University Extension: The leaves on my houseplant are covered with a sticky sap. There are also small bumps on the stems.
  3. Iowa State University Extension: What is this sticky substance all over the table, floor, and lower leaves of my houseplant?

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Sources: the university extension and horticultural society pages listed above. Last reviewed October 2026.