How Can I Control Mealybugs?

Do you want to control mealybugs using the biological control method?

Do you want to control mealybugs using low-risk (organic) insecticides?

Do you want to control mealybugs using isopropyl alcohol treatment?

Do you want to control mealybugs using broad-spectrum insecticides?

Do you want to use residual, foliar sprays?

Many natural enemies feed on and kill mealybugs on fruit trees and woody ornamental plants in the landscape. Common parasites include species in the genera Coccophagus, Leptomastix, Allotropa, Pseudaphycus, and Acerophagus. Naturally occurring predators of mealybugs include lady beetles, green and brown lacewings, spiders, minute pirate bugs, and larvae of predaceous midges. The mealybug destroyer lady beetle, Cryptolaemus montrouzieri, is the most important of these predators in many areas. The mealybug destroyer can be purchased for augmentative release. Preserve naturally occurring biological control agents by avoiding the use of broad-spectrum insecticides for any pests in the area.

Insecticidal soaps, horticultural oil, or neem oil insecticides applied directly on mealybugs can provide some suppression, especially against younger nymphs that have less wax accumulation. Be sure to test for the phytotoxicity of these materials before treatment.

On small infestations on houseplants, a 70% or less solution of isopropyl (rubbing) alcohol in water may be dabbed directly on mealybugs with a cotton swab to kill or remove them. Test the solution out on a small part of the plant 1 to 2 days beforehand to make sure it does not cause leaf burn (phytotoxicity). In some cases, a much more diluted solution may be advisable. Where infestations are extensive, a 10-25% solution of isopropyl alcohol can be applied with a spray bottle.

Some residual insecticides, including pyrethroids, are labeled for some situations but may not be much more effective than soaps and oils and can be devastating to natural enemies. Be aware that none of the available insecticides will likely provide complete control of all individuals, and that you will need to monitor and treat again as needed. When infestations become severe, consider discarding houseplants rather than repeatedly treating them with insecticides.

Products containing the systemic insecticide dinotefuran may reduce mealybug numbers on some landscape plants, and plant spikes or granules containing the related insecticide imidacloprid may reduce mealybug crawler numbers on houseplants. These neonicotinoid products are less reliable against mealybugs than against other piercing-sucking insects in many situations. Their use should be avoided when possible, especially on flowering plants, because of potential negative impacts on natural enemies and pollinators.

If mealybugs are somewhat exposed, it may be possible to reduce populations on sturdy plants with a high-pressure or forcible spray of water. Repeat applications at several-day intervals may be necessary. Avoid unnecessary applications of nitrogen fertilizer on plants with mealybugs. High rates of nitrogen coupled with regular irrigation may stimulate tender new plant growth as well as mealybug egg production. If you had a history of serious mealybug problems, consider using only plant species that are not prone to mealybugs for at least a year or two to reduce mealybug density and harborage potential.