Telling Them Apart
University of Wisconsin Extension describes mealybugs as soft-bodied insects covered with white, waxy, cottony material. Adult females are rounded, wingless and about 1/16 inch long. They gather in sheltered places such as leaf axils, along leaf veins and where stems meet.
Scale insects look different. Adults attach to a stem or leaf and stop moving, and they form a hard, dome-shaped shell that is usually brown, tan or gray. Soft scales also leave behind sticky honeydew.
The Honeydew Clue
Sticky residue on leaves, furniture or the floor under a plant often points to mealybugs or scale. Honeydew can grow sooty mold, a black coating that blocks light on the leaf surface.
Check the undersides of leaves and every stem joint, not just the visible top growth. Both pests favor hidden spots.
Why One Spray Is Rarely Enough
The waxy coating on mealybugs and the shell on scale protect the insects, and eggs tucked into crevices are hard to reach. University of Wisconsin Extension notes that washing rarely eliminates all the pests, so repeated treatment is needed.
Manual Removal First
Start by removing what you can see. For a light infestation, this may be most of the work.
Alcohol Spot Treatment
Extension guidance suggests wiping the insects away with a cotton swab or cloth dipped in rubbing alcohol. Test the alcohol on a small area of the plant first, because some plants have leaves that are sensitive to it. Work leaf by leaf and stem by stem, and do not skip sections that look clean.
Washing and Pruning
A moderately strong spray of warm water can knock insects off. If a stem or leaf cluster is too heavily infested to treat insect by insect, cut it off and discard it away from your other plants.
Other Treatments for Persistent Cases
If hand removal does not keep up, extension sources suggest insecticidal soap or horticultural oils, as well as registered insecticides sold at garden centers. Use only products labeled for houseplants and for the pest, and follow the label for rate and frequency. Do not increase the dose to speed things up.
Expect to treat more than once. Check the plant a few days after each treatment and repeat until you stop finding new insects.
Isolating the Plant
Move an infested plant away from the others as soon as you notice it. Mealybugs can spread between plants whose leaves touch or that share a tray. Keep the plant apart for several weeks after you last see an insect, not just until it looks clean.
Building a Routine That Prevents Reinfestation
Inspect new plants before bringing them home and keep them apart from your collection at first. Then check your plants regularly, looking at new growth, leaf undersides and stem joints. Finding a few insects early makes treatment much easier.
When It's Time to Let Go
Some infestations do not respond. University of Wisconsin Extension notes that for severe infestations, especially on roots, discarding and replacing the plant is often the most practical choice. That protects the plants around it.
Browse more diagnostic guides for common plant pests.
