Harlequin bugs are attractive shield-shaped insects in the stink bug family and are usually black with bright red, yellow, or orange markings. Adult bugs are 3/8 inch long.

Identification

Harlequin bugs can be confused with Bagrada bugs, an invasive species, but are much larger and lack the white markings characteristic of Bagrada bugs. Harlequin bugs may also be confused with stink bugs. Coloration in bugs varies. The consperse stink bug, Euschistus conspersus, is usually gray brown to green with speckled black legs. Don't confuse the consperse stink bug with the rough stink bug, Brochymena sulcata, which is a predator. The brown marmorated stink bug, often confused with the rough stink bug or consperse stink bug, is an invasive species and serious pest of many fruit and fruiting vegetable crops. Two other common species are the Say stink bug, Chlorochroa sayi, and the southern green stink bug, Nezara viridula. The Say stink bug is green with a white rim around its borders. The southern green stink bug is bright green and larger than other stink bugs.

Life Cycle

Drum-shaped eggs with circular "lids" are laid in clusters on foliage. The nymphs, nearly round and often brightly colored, remain close together at first but scatter as they grow. They pass through four or five molts, gradually developing wings and adult coloration. Adults overwinter on the ground under leaves and become active in March or April. Stink bug infestations originate when adults fly in from weedy areas, often from the edges of sloughs and creeks where blackberries grow. Damage is often limited to the edges of fields near these areas, but in years with a lot of spring rain and late weed growth, stink bugs may be numerous and damage more widespread.

Damage

Harlequin bugs suck fluids from plant tissue. They leave yellow or white blotches on areas of leaves where they have been feeding; heavy infestations can cause plants to wilt, turn brown, and die.

Solutions

Handpick bugs or their eggs. Eliminate groundcovers or weedy areas (especially mustards) in early spring before populations build up. Destroy old cole crop plants and mustards because they provide breeding areas. Insecticides are generally not recommended in gardens for stink bugs. Parasites and general predators may contribute to control.