brown scale (bumps) on the back of a leaf

Brown soft scale on the back of a leaf. It commonly is found close to the leaf veins.
Lesley Ingram, Bugwood.org

Updated: March 26, 2021

Signs and symptoms of scale insects on indoor plants

  • Soft scales are sucking insects that attack a wide variety of plants. Heavy infestations may cause leaf yellowing, stunting, and dieback.

  • Soft scales such as brown soft scale and the hemispherical scale are common pests of indoor plants.

  • They appear as raised bumps on leaves and stems, vary in color, and can be scraped off.

  • They produce honeydew and sooty mold may be present on leaves below infested branches.

drop of sticky honeydew on the leaf of an indoor citrus plant
Drop of sticky honeydew on the leaf of an indoor citrus
Photo: Whitney Cranshaw, Colorado State University, Bugwood.org
  • Armored scales are not common on most indoor plants, but maybe a problem on some orchids.

  • They are flattened, small, and do not produce honeydew.

  • They are difficult to control on orchids, because they may be protected under the sheaths. Careful examination of the plants is essential to control. The scale bodies may be scraped off and treated as for other scale on indoor plants.

  • Examine the scale for parasite activity, especially if the plant has been outdoors. Parasitized scales will appear dark in comparison to normal scale insects.

Management strategies

  • Infested plants should be quarantined.

  • Heavily infested plants should be discarded.

  • Wash off or crush any visible scale insects. Often they are found on the stems, underside of leaves, or along the leaf mid-veins. 

  • Treat with an insecticidal soap or horticultural oil labeled for indoor plants or a houseplant spray that is registered for use on indoor plants.

  • There are also systemic indoor plant insecticides that are labeled to be used in the soil as a soil drench to help control scale.

  • Be sure the plant and insect are on the label and follow all directions carefully. 

  • Some indoor plants are sensitive to chemical sprays, especially soap. Read the product label. 

  • Multiple treatments are necessary.

  • Outdoors scale is kept under control by beneficial insects. Spray your indoor plants with insecticidal soap or oil labeled for indoor plants before bringing them back indoors in the fall. 

  • Closeup of brown soft scale
    Photo: Whitney Cranshaw, Colorado State University, Bugwood.org

    closeup of brown scale on the back of a leaf
  • Heavily infested fern

    Heavily infested fern with brown scale