How to Identify and Manage Mealybugs

These small white insects are a big problem for the interior landscape. They love tropical foliage, especially plants such as pothos and ivy.

There are several species that attach to tropicals and sometimes can be hard to identify. Mealybug populations do no explode overnight, they usually have been present for a long time just as low population levels. When at low levels, they can be hard to find because of their ability to hide in plant cracks and crevasses.

Why Are Mealybugs So Destructive?

Mealybugs can damage plants while feeding by injecting toxins into the plants, causing deformation. Also, mealybugs (really a type of soft scale) excrete honeydew as they feed. Unsightly sooty molds will often grow on the honeydew. This honeydew can also get on walls, furniture, floors and other items making them sticky. At high levels, mealybugs can cause plants to defoliate and even cause plant death.

How to Identify Mealybugs

MealbugsSoft-bodied, flat and waxy, mealybugs can also be identified by their oval shape and body segmentation. These insects can also resemble cottony spots, especially as females lay eggs encased in a waxy cover. Adult males, however, look completely different: they have wings and look more like small flies and are not often seen. Damage caused by mealybugs includes yellowed and dropping leaves, distorted growth, and sooty black mold.

The Life Cycle of a Mealybug

A mealybug’s life cycle depends on the species, but as an infestation grows it can cause major harm to plants, especially for interior landscaping. Females go through four developmental stages—or instars—and adult females can lays as many as 600 eggs. The eggs hatch in 6 to 14 days, and the crawlers—the first instars—crawl to new places to feed and anchor themselves there. Male mealybugs go through five instars, feeding in their first two instars and developing wings when they mature into adults.
Life is short for adult mealybugs: females die shortly after they lay eggs, and males live for a day or two after fertilizing females. Adult male mealybugs have no mouthparts, leaving them no way to feed. They sometimes can be mistaken for fungus gnats.

Do You Have a Mealybug Infestation?

Clear indicators:

  • Cotton / waxy deposits on plant
  • Black, sooty mold
  • Yellowing and dying leaves
  • Distorted or stunted plant growth

It’s Time to Take Back Control

Once you’ve identified your problem, you need to think about management options. Often removing and destroying any infested plants may be the most economical treatment.

Biocontrol for mealybugs can be somewhat tricky and it helps to know which mealybug species you are dealing with. There are some commercially available options like Cryptolaemus, the mealybug destroyer. This ladybird beetle works best in mass planting and not individual containers. It’s also not the best choice for long tailed mealybug. Another beneficial is the green lacewing. Being these are generalist predators they can help with many pests in addition to mealybugs.

With mealybugs, it’s best to get someone knowledgeable on biological control involved. This way you can get the right predator for your mealybug species.

For spray options, horticultural oil works well if you get the oil in contact with the pest. This can be hard because of their waxy coating and their ability to hide in protected areas making it difficult to get good spray coverage. Another option are systemic insecticides. These are compounds like Safari (dinotefuran) and Flagship (thiamethoxam) and can be used as a drench on the interior landscape. They and can be very effective when used appropriately.

Pest control labels vary between states and the pesticide user bears the responsibility of consulting the pesticide label and adhering to the law. Always read the label before a pesticide is applied to make sure it is legal to apply on your site, in your state and the plant material.

Preventing Mealybug Infestations

Mealybugs can be some of the toughest, most troublesome pest for the interior landscape because they can be so damaging. By inspecting plants before you purchase and introduce them into your accounts, you can be the best defense against a nasty mealybug offense. If a problem is found, remove or treat the plants immediately.

Battling other common indoor plant pests? Check out my Professional’s Field Guide to Plant Pest Control for information on Spider Mites, Whiteflies, Fungus Gnats, Thrips, Aphids, and Scale insects.

Photo by Alexlutor

Suzanne Wainwright-Evans is an Ornamental Entomologist specializing in integrated pest management. Suzanne has been involved in the Green Industry for more than 18 years with a primary focus on biological control and using pesticides properly. She is a graduate of the University of Florida with degrees in both Entomology and Environmental Horticulture. She has worked throughout the United States and internationally consulting to greenhouses, nurseries, landscapers and interiorscape companies.

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