What is a harlequin bug?

By Chelsie Vandaveer

January 7, 2004

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The harlequin bug (Murgantia histrionica (Hahn)) is native to Central America. It appeared in the southern U.S. shortly after the Civil War and quickly became a pest on the crucifers—cabbages, radishes, broccoli, horseradish, and other members of the Brassicaceae.

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Harlequin bugs begin life in tiny 'barrels'; the eggs even have two black bands that appear like hoops holding the staves together. The eggs are laid in the early spring on the underside of the host's leaves. If the temperatures are warm, the eggs will hatch in as few as four days; if the temperatures are cool, the eggs may take a month.

Harlequin bugs feed by piercing the plant and sucking the sap. The initial damage appears as a white or yellow spot on the leaf. An infestation of harlequin bugs sucks a plant to death; the plants wither, brown, and die.

Like the medieval prankster, Harlequin, the insects are aposematically (conspicuously) colored in black and red--a warning to potential predators. The common name is more apt than first thought—the insects sequester (absorb and retain) glucosinolates, the chemicals that give the crucifers their peppery taste. A study done by A. Aliabadi, J.A. Renwick, and D.W. Whitman (2002) found that a harlequin bug can have 20 to 30 times more glucosinolates stored in its body than is present in the sap in its intestine. Certainly, the peppery bugs are a practical joke on any bug-eating bird.

The Cooperative Extension Service of Clemson University has posted a photograph of the harlequin bug. To view this colorful pest, click on the link:

http://hgic.clemson.edu/factsheets/Graphics/cabbageins/harle.htm

(Compiled from: "Harlequin Bug", IPM, North Carolina State University; "Cabbage, Broccoli, and other Cole Crop Insects", Randall P. Griffin, Entomologist, Cooperative Extension Service, Clemson University, 1999; "Harlequin Bug", Marie A. Knox, Featured Creatures, IFAS, University of Florida, 1998; and "Sequestration of glucosinolates by harlequin bug Murgantia histrionica", A. Aliabadi, J.A. Renwick, and D.W. Whitman, Journal of Chemical Ecology, Sept 2002)

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