Seeing a white mass on your houseplants? There may be mealybugs

Mealybug feeding causes stunting and yellowing of the leaves, and eventual leaf drop.

Credit: Contributed

Credit: Contributed

Mealybug feeding causes stunting and yellowing of the leaves, and eventual leaf drop.

While (finally) watering my houseplants, I noticed that one of the (many) ones turning yellow was not doing so because of lack of water. It has mealybugs. Do as I say, not as I do.

Huh, will you look at that? Upon closer inspection, I just discovered that it has two-spotted spider mites as well.

I shouldn’t be surprised as this is the time of year that many houseplant insect problems show up in full force. I haven’t been paying much attention to them recently due to the business of the holidays.

After giving all of them a good soaking, I also inspected them closely and removed the one that was infested. Fortunately, none of the others are showing any signs or symptoms of problems.

Several species of mealybug feed on greenhouse, nursery and landscape plants. Typically, I see the species that is on houseplants, although I have seen Miscanthus mealybug on the namesake plant.

Mealybugs are quite common on houseplants, particularly succulents in my experience. Last year I had a bad infestation on my jade plant; it was so heavy that it killed the plant.

Mealybugs are a type of scale (I did not know that!) that have piercing-sucking mouthparts. They insert their mouthparts in the plant and suck out the juices. They also excrete the sticky substance known as honeydew.

A black substance known as sooty mold tends to grow on the honeydew. If you see this blackish substance on the plant’s surface or even on the floor, table, or other objects, you have a piercing-sucking insect such as a mealybug, aphid, or other.

Most people don’t notice mealybug in the early stages. They are tiny and feed in the crevices of the plant, usually at the base of stems. As numbers increase, you may see them crawling on the stems.

A mealybug infestation is usually discovered when one sees the fluffy white mass that covers the insect. It looks like cotton remnants that got stuck in the base of the stems. If you scrap the cotton-like fluff, you will find the pinkish mealybug.

Mealybugs are a nemesis in the house or a greenhouse. They are difficult to control and multiply fast. The cottony mass prevents sprays from penetrating and contacting the insect. And because they are hunkered down in the nooks and crannies, it’s even harder to spray.

Systemic houseplant insecticides are effective. However, it may take time and if infestations are heavy, the plant may not make it. Combine the chemical with mechanical tactics by taking a cotton swab dipped in rubbing alcohol and scraping those that you can see off the plant.

Since my plant is in bad shape (it might even have aphids as well), I am going to employ the systemic insecticide and see what happens. Stay tuned!

Next week I will discuss two-spotted spider mites in detail. Check your houseplants!

Pamela Corle-Bennett is the state master gardener volunteer coordinator and horticulture educator for Ohio State University Extension. Contact her by email at bennett.27@osu.edu.

The white mass at the base of the stems is mealybug.

Credit: Contributed

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Credit: Contributed

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