What Is the Cottony Substance on My Indoor Plants?

Overview

Mealybugs have a distinctive appearance that makes them one of the easiest insects to recognize. A mealybug’s body is oval and about 1/4 inch long. The body is completely concealed by 1/2 inch white wax filaments that give it a cottony appearance. Mealybugs are often found in the axis where a leaf attaches to a stem.

Damage

Mealybugs feed by sucking sap from the leaves and stems of plants. Infested plants become weak from the loss of sap and become yellow, stunted and deformed. In heavy infestations the plant may die. As they feed, mealybugs secrete a sticky substance called honeydew. A fungus called sooty mold feeds on the honeydew, causing black or dark gray spots on the leaves. If found early honeydew is easily cleaned from the leaves.

Life Cycle

Mealybugs lay 300 or more orange eggs that are enclosed in a white egg sac. The egg sac is usually deposited in the axis where a leaf is attached to the stem. Mealybugs don’t go through a larval stage like most insects, but instead hatch as tiny replicas of their parents called nymphs. The nymph stage of a mealybug’s life is the only time when it can move about freely. The freedom to move about doesn’t last long. Nymphs begin looking for a place to settle down as soon as they hatch. Once they find a good spot, they insert their beaks into the plant and begin sucking sap. As they feed, fine white filaments grow around their bodies giving them a characteristic cottony appearance. Once they begin feeding, mealybugs usually stay in the same location for their entire lifespan of four to 10 weeks.

Control Spread

Mealybugs are difficult to control and they quickly spread to other houseplants. Unless the plant is valuable the best solution may be to discard it. If you decide to try to save the plant, keep it isolated from other houseplants. Thoroughly clean any tools used on the infested plant and wash your hands immediately after working with it.

Home Remedies

Home remedies are as effective as insecticides against mealybugs. First, hand pick the insects and egg sacs from the plant. Use a cotton swab saturated in alcohol to kill the insects if you don’t want to hand pick them. Another good control measure is to use a syringe to create a forceful spray of lukewarm water against the plant. This will dislodge insects and also helps to control nymphs that are difficult if not impossible to hand pick. Examine the plant daily for new insects.

Insecticides

If home remedies don’t get mealybugs under control you may want to try insecticides. Always read insecticide labels carefully. Choose a product that is designed specifically for houseplants. It should contain one or more of these ingredients: insecticidal soaps, neem, pyrethrin, bifenthrin, permethrin or resmethrin.

Keywords: cottony mealybugs, houseplant mealybug insect, houseplant insect, houseplant cotton substance

About this Author

Jackie Carroll is a freelance writer with more than 15 years experience. Her home & garden and nature articles have appeared in "Birds & Blooms" and "Alamance Today." She holds a Bachelor of Science in medical technology from the University of North Carolina.

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