Scale Bugs on House Plants

Look over new houseplants closely to make sure they do not suffer scale before bringing them into the home.

A houseplant infected with scale insects (Coccidae, Diaspididae and other families) will have gray or brown bumps along its stems and beneath the leaves. The tiny spots measure only 1/16 to 1/8 inch of an inch in diameter.

Effects

The scale insect secretes a waxy substance that it uses to cover its body in an armor shell-like coating. Hidden beneath the protective hard covering, the insect uses its powerful mouth to attach itself to the plant's tissue to suck the nutrients and water. The insect can cause the plant's growth to become stunted and deformed. In severe cases the plant may loose foliage.

Considerations

The insect produces a substance known as honeydew, which is the excreted waste substance that results from the insect's voracious feeding. The honeydew produces a noticeable sticky substance on the plant. Allowed to persist, the honeydew will often become moldy.

Solution

In a light infestation, scrape the scales away using fingernails or a rough cloth, or take a cotton swab and lightly dab the insects with rubbing alcohol. If the plant suffers numerous scale insects, consider using an insecticidal spray or soap that contains resmethrin, bifenthrin, pyrethrin or permethrin, according to the Iowa State University's website.

References

• Iowa State University: Scale Insects
• University of Minnesota: Houseplant Insects
• Colorado State University: Managing Houseplant Pests
• Cornell University: Scale on Houseplants
• Purdue University: Scale on Houseplants
• State of Connecticut: Houseplants

Resources

• Iowa State University: Scale Insects on Houseplants
• Cornell Cooperative Extension: Scale on Houseplants