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MEALYBUGS

Steven D. Frank, Extension Entomologist

CAUTION: This information was developed for North Carolina and may not apply to other areas.

General Information

MEALYBUGS, Citrus mealybug, Planoccocus citri (Risso) and other species; Pseudococcidae; HOMOPTERA

There are several species of mealybugs that can be pests of greenhouse, nursery, and landscape plants.  The most common of these are the citrus mealybug and longtailed mealybug though other species including Madeira, mealybug (Phenacoccus madeirensis), miscanthus mealybug (Miscanthicoccus miscanthi), and various root mealybugs also occur.  In general mealybugs cause similar damage symptoms and are managed in similar ways.  Female mealybugs are soft oval insects without wings. They are up to 3 mm long. Some species are covered with fluffy wax and others have long, tails of fluffy wax. Male mealybugs are tiny, gnatlike insects with two wings and long tails of white wax. Mealybug eggs are very small but and covered by a conspicuous dense, fluffy, white mass of wax called the ovisac. Very young nymphs are flat, oval and yellow. Older nymphs of some species are covered with fluffy, white wax.

Biology

Mealybugs are pests of ornamental crops indoors and outdoors across the world. They are most active in warm, dry weather. Most species of ornamental plants can be infested with mealybugs. Mealybugs damage plants by inserting their threadlike mouthparts into any part of the plant and sucking out sap. Mealybugs excrete honeydew, a sweet, sticky liquid. Sooty molds often grow in the honeydew causing infested plants to turn black. The citrus mealybug has a toxin in its saliva which causes its host plants to drop leaves and buds. Heavily infested plants are disfigured by the mealybugs, their ovisacs, honeydew and sooty molds.
Female mealybugs have no wings and must be transported directly to or near the next host plant. They can travel short distances by crawling or the very young nymphs may be blown about by the wind or carried on the feet of birds. Small numbers of mealybugs are easily overlooked as they tend to wedge into crevices on plants. Mealybugs are usually found at the base of stems (or petioles of plants with long petioles such as African violets). After the first batch of eggs hatch, the infestation becomes very noticeable. As their numbers increase, mealybugs of all sizes can be found crawling around or feeding on all surfaces of the plant.

Each female usually lays from 200 to 600 eggs in the tick ovisac. Some species of mealybugs give birth to live young. After several weeks, the nymphs develop into adults. Male nymphs secrete a tiny, fluffy cocoon and develop into winged adults. Males then fly about seeking females to mate with.

Control

Mealybugs are not easy to control. This is because the eggs are enmeshed in waxy fluff and thus relatively water proof.  Likewise adults and nymphs can be covered in wax to varying extents and obscured in plant nooks and crannies where it is difficult to get thorough pesticide coverage.

For this reason systemic insecticides may offer the most reliable control because they make the plant toxic to feed on rather than relying on contacting the insect directly.  If a contact insecticide is used be prepared to repeat the applications two or more times to kill nymphs that hatch from protected eggs and adults or nymphs that were protected by plant tissue.  If an infestation is discovered early enough on a few cherished house plants, the mealybugs may be removed by a cotton swab dipped in alcohol or fingernail polish remover. Keep an eye on the plants for a few weeks to make sure no mealybugs are overlooked.

 
  Table 1.  Selection of chemicals available for management of mealybugs on ornamental plants. G = Greenhouse, L = Landscape, I = Interiorscape, N = Nursery

Active ingredient

Trade name

Labeled location

Signal word

IRAC
MOA
group

Compatible with
beneficials

abamectin

Avid

G, L, N

Caution

6

Yes

acephate

*Orthene

G, N, L

Caution

1B

No

acetamiprid

TriStar

G, N, L

Caution

4A

Yes

buprofezin

Talus

G,N

Caution

16

Yes

dinotefuran

Safari

G, N, L, I

Caution

4A

Yes

flonicamid

Aria

G, N, L

Caution

9B

Yes

horticultural oil

*many

G, N, L, I

Warning

-

Yes

imidacloprid

Marathon II

G, N

Caution

4A

Yes

imidacloprid

*Merit

L, I

Caution

4A

Yes

insecticidal soap

*many

G, N, L, I

Warning

-

Yes

pymetrozine

Endeavor

G, N, L, I

Caution

9B

Yes

pyriproxyfen

Distance

G, N, L, I

Caution

7C

Yes

thiamethoxam

Flagship 25 WG

G, N

Caution

4A

Yes

* Suitable for homeowner use. For more choices, see the NC Pesticide Manual.

Useful References: http://mrec.ifas.ufl.edu/lso/Mealybugs.htm


Recommendations for the use of chemicals are included in this publication as a convenience to the reader. The use of brand names and any mention or listing of commercial products or services in this publication does not imply endorsement by the North Carolina Cooperative Extension Service nor discrimination against similar products or services not mentioned. Individuals who use chemicals are responsible for ensuring that the intended use complies with current regulations and conforms to the product label. Be sure to obtain current information about usage and examine a current product label before applying any chemical. For assistance, contact an agent of the North Carolina Cooperative Extension Service in your county. © 2001 NC Cooperative Extension Service

Other Resources


Originally Prepared by: James R. Baker, Extension Entomologist, Emeritus
May 1994 (Revised) April 1998.  Revised August, 2010 by S.D. Frank. Pink Hibiscus mealybug photo by USDA.

ENT/ort-19
Web page last reviewed January, 2011 by the webperson.