HPIPM:Harlequin Bugs

Author: Jay D. Donahue & Michael J. Brewer

Harlequin bugs can be a problem after mild winters, but low densities are unlikely to cause damage which will be regained economically by insecticides.

Identification (and life cycle/seasonal history)

Harlequin bugs are shield-shaped flat bugs, easily identified because of their bright, shiny black and red coloration. The triangular plate on the top of the thorax is black with a cross shaped mark of red in the center. Harlequin bugs smell bad at all life stages. Harlequin bugs overwinter mostly as adults in our area, hiding under crop residue and in other protected sites. They become active in mid-spring and begin the feed on wild crucifers. They move into crop stands by early summer, and begin to lay eggs on leaves. After hatching, harlequin bug nymphs usually remain on the same plant, feeding for about two months before becoming adults. Unless the weather remains unseasonably warm, only one generation occurs per growing season.

Plant response and Damage

Harlequin bugs feed by sucking sap from crucifers. If young plants are fed on, the growth is distorted and slowed, and the growing point may die. Plant tissue around the feeding sites often turn cloudy. Harlequin damage is more likely after mild winters.

Cultural Control

Crop residue should be destroyed immediately after harvest to reduce local populations. Other cover, such as vegetation near field edges should be reduced to minimize overwintering success.

Host Plant Resistance

The cabbage varieties Copenhagen Market 86, Headstart, Savoy Perfection Drumhead and Early Jersey Wakefield; the cauliflower varieties Early Snowball X and Early Snowball Y, and radish varieties White Icicle, Globemaster, Cherry Belle Champion, Red Devil and Red Prince have all been recognized as resistant to harlequin bugs.

Biological Control

Harlequin bugs are subject to attack by some predators, but have developed effective chemical defenses of their own. If harlequin bugs are controlled with insecticides, however, natural enemy populations of other more important pests, such as aphids and caterpillars, will be disrupted.

Due to constantly changing labels, laws and regulations, the sponsors of this web site assume no liability for the suggested use of any chemicals noted in the management section. Contact your local pest management personnel for current information on labeled pesticides that can be used for the intended plant disease, insect pest or weed.