Insecticide For Root Mealybugs

Root mealybugs in the genus Rhizoecus have adapted to subterranean life. These include the ground mealybug, Rhizoecus falcifer, Rhizoecus americanus, and the newly introduced hibiscus mealybug, Rhizoecus hibisci. One of the most familiar root mealybugs in North Carolina is Pritchard’s mealybug, Rhizoecus pritchardi, that feeds on the roots of African violets and other plants. These root mealybugs differ only in microscopic characters. Adult females are ¹/₁₆ to about ¹/₈ inch long, slightly flattened, and rounded on each end. The body is bluish white but covered with a shallow, white, fluffy bloom. They resemble large, white springtails but move much more slowly. Some species even secrete slender filaments that form a netting over the insect. They also secrete a powdery, white fluff that gives the soil a bluish tint. These mealybugs almost or completely lack eyes, and the antennae are short. Females lay at least six eggs in a fluffy, white sort of nest. The nymphs resemble females but are smaller. When potted plants are irrigated, root mealybugs sometimes crawl out of the drainage holes and infest plants nearby.

Root mealybugs are often overlooked as they are tiny and infest on roots.

Root mealybugs feed on the roots of ornamental plants including Achillea, Arctostaphylos, African violet, anemone, bamboo, Bermuda grass and other ornamental grasses, chrysanthemum, Geum. ginger, gladiolus, iris, hibiscus, Polygala, Robinia, and palms including queen, majesty, fishtail, triangle, kentia, lady, pygmy date, and MacArthur palms. These mealybugs can be found feeding on the roots of many plant families.

Because mealybugs are susceptible to systemic insecticides, I recommend treating infested plants with imidacloprid or some other systemic insecticide. Most of the systemic insecticides found in big box stores and garden center should be effective as long as they are labeled for residential use. Some formulations of systemic insecticides are labeled only for landscape use. Houseplants can be placed outdoors for treatment with such labeled insecticides. Tender houseplants should probably be placed in shade to prevent sun scald.