Scale on Houseplants

Scale insects come in a variety of shapes, sizes, types and colors. I call scale insects the sneaky killers because they often go unlooked when compared to their flashier friends such as mealybugs, spider mites and aphids. Scale insects come in a variety of shapes but one thing they all have in common is a waxy or shell like covering. Most scale insects we see are tan or brown but there are some that have a white fuzzy covering similar to mealy bugs. They are typically less than ¼” in length which helps them blend into the plants the live on. The photo to the right shows both adult and nymph or “crawler” scale insects. Scale insects feed on plants by sucking sap out of the leaves or stems. Most often the infestation is discovered by the stunted growth of the plant or the presence of “honey dew” which is a sticky substance excreted by the insects. Control can be difficult since the waxy covering of the insect protects it from many insecticides. For lightly infested plants use a q-tip and rubbing alcohol to rub off all the scale insects you can see. For heavier infested plants you will want to move them outside and spray using a chemical with the active ingredients that include insecticidal soaps, pyrethrin, rotenone, resmethrin and acephate. You will have to thoroughly cover the plant and will need to spray every week or so for a month, depending on the product label, to get an effective level of control. If the plant will regrow after being pruned back cut off the areas with the heaviest infestation and then treat. If the plant is heavily infested it might be best to throw the plant away and start over.

Have questions? Contact our office where our Horticulture Extension Agent will assist you with questions.

Phone: (316) 321-9660

Email: callae@ksu.edu