What’s bugging you? Signs of mealybugs on delicate houseplants

A photo of mealybug.
A photo of mealybug.

Fall has officially arrived and a lot of you are getting ready to move your more delicate houseplants inside for the winter.

Before carrying them inside, you need to check for pests. Once inside your house, without the controls offered by Mama Nature, they can become a major problem very quickly.

One of the more common of these pests are mealybugs. These are soft-bodied, sucking insects that look like the fuzzy end of a Q-tip. This white, cottony covering is secreted by the bug to protect them and their eggs from predators and parasites. Under the coating, females vary in color from pink to yellow to grey.

Mealybugs feed by sucking large quantities of fluids from their host plants. This large volume is necessary because of the limited amount of protein in the sap. The excess fluid is excreted in the form of a sticky substance called honeydew. This drops onto the leaves below the mealy bug, forming a substrate perfect for the growth of sooty molds.

Most mealybugs are colonial, joining forces in the nooks and crannies of the plants. Generally, they congregate in leaf axils (where the leaf joins the stem), growing tips or along leaf veins. This habit of playing hide-and-seek makes them difficult to control with topical pesticides.

Ants will also show up with mealybugs. They are attracted to the honeydew. Many species of our local ants “farm” mealybugs. They will transport them from plant to plant; protecting them from predators and parasites.

When it comes to control, goof light, light fertilizer and judicious watering will help your plant to be more resistant to pests and diseases. Because of their waxy coating, topical pesticides have limited control. A systemic is a much better option. Look for one containing the active ingredient “imidacloprid.”

In severe cases, significant pruning and proper disposal of the cuttings may be necessary. If you prune, double bag the cuttings immediately. If a mealybug is knocked off of a cutting, it can easily crawl back onto your vulnerable plants. Savers insecticidal soap can help to control mealy bugs.

Spray the plant thoroughly every week for four weeks. This length of time is required to stop new nymphs. You can’t kill an egg. For light infestations, dip a Q-tip in alcohol and dab it on the bug. Repeat this procedure every week until the problem is solved. Just to be on the safe side, test the soap and alcohol on a small portion of the plant to see if they might be sensitive.

If your plant is sturdy enough, you can flush the bugs off the plant with a strong jet of water. For the really adventurous, you can squish the little buggers between your thumb and forefinger.

Tim Lockley, a specialist in entomology, is retired from a 30-year career as a research scientist for the U.S. Department of Agriculture. For answers to individual questions, please send a stamped, self-addressed envelope to Tim Lockley, c/o Sun Herald, P.O. Box 4567, Biloxi MS 39535.