Stink bugs
Click for larger image Adult harlequin bug and its black and white, barrel-shaped eggs (Hemiptera) on collards (Brassica)

Stink bugs are attractive and distinctive insects that are generally easy to identify. Ranging in size from 1/4 to 1 inch long and about half as broad, they are shield-shaped with a triangle-like horny scale on their back. Also, as the name indicates, many stink bugs do produce an offensive odor when disturbed. The most common pest species are green, brown, gray, or yellow and some have red or yellow markings. Their host plants include blackberry, cabbage and other members of the mustard family, corn, tomato, eggplant, bean, soybean, and trees such as apple, peach, pecan, and cherry. Stink bugs may also be found on ornamental plants including columbine, snapdragon, and sunflower. The harlequin bug, Murgantia histrionica, a red and black-spotted species of stink bug, is an important pest of crops in the mustard family in the southern United States. The green stink bug, Acrosternum hilare, and brown stink bugs, Euschistus spp., can be of economic importance in soybean fields primarily by reducing seed quality and quantity. A few species of stink bugs are predatory on other insects.

Symptoms and Diagnosis

In the "true bug" group, stink bugs feed by inserting their mouth parts into the leaves, flowers, buds, fruit, and seeds of host plants and sucking plant sap. Large infestations of stink bugs may cause plants, especially small plants and young tender growth, to wilt, become stunted and misshapen, or die. Other damage includes yellow or white blotches on leaves; misshapen or aborted fruits, seeds, and buds; calluses, blemishes or depressions; and black pits on nuts. Tomatoes exhibit pale yellow spots and a white pithy area just under the skin at the puncture site. Peaches and other fruits may develop scarring and dimpling resulting in cat-facing or a pitted appearance. The seeds in soybean pods may be deformed, small, discolored, or shriveled.

Life Cycle

The stink bug overwinters as an adult in protected areas such as under dead weeds, leaf litter, or the bark of trees. In early summer, the female lays clusters of eggs on the underside of leaves. These eggs are barrel or keg-shaped with a circular lid. In one to three weeks, the young hatch into wingless nymphs that resemble small adult stink bugs, although the coloration may differ from that of the adult. The nymphs will molt several times before developing wings and becoming an adult. The number of generations per year depends on the species.

Integrated Pest Management Strategies

1. Sanitation. Control weeds in susceptible crops and in areas adjacent to gardens to decrease breeding and overwintering habitat. It is important to remove weeds early in the growing season before stink bug populations increase or the loss of habitat may force pests to move into the garden.

2. Collect insects. Hand pick and destroy eggs and bugs.

3. Use natural controls. Encourage other natural predators such as parasitic wasps and flies by growing small-flowered plants. The unpleasant odor produced by stink bugs deters many predators but several bird species do consume these pests.

4. Use trap crops. Plant trap crops of mustard and treat that area with an appropriate pesticide.

5. Use insecticides. If damage is severe, use insecticidal soap, sabadilla, pyrethrin or permethrin (Eight).

Organic Strategies

Strategies 1, 2, 3, and 4 are strictly organic approaches. For an organic approach to Strategy 5, consult the Organic Materials Review Institute (OMRI™) for appropriate insecticidal soap and pyrethrin products.

More images:

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Tiny, black and white, barrel-shaped harlequin bug eggs (Hemiptera) on collards (Brassica)
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Black and white, barrel-shaped harlequin bug eggs (Hemiptera) on collards (Brassica)
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Adult harlequin bugs (Hemiptera ) on horseradish (Armoracia rusticana)
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Green stink bug larvae/nymphs (Hemiptera); note shield shape, wing buds, and antennae
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Stink bug larva/nymph (Hemiptera) on tomato fruit (Lycopersicon); note, wingbuds
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Close-up of barrel-shaped stink bug eggs and larvae or nymphs (Hemiptera)
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Barrel-shaped stink bug eggs and larvae or nymphs (Hemiptera)
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Barrel-shaped stink bug eggs and larvae or nymphs (Hemiptera)
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Green stink bug adult (Hemiptera)
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Stink bug (Hemiptera) damage to tomato fruit (Lycopersicon)
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Close-up of stink bug (Hemiptera ) damage to tomato (Lycopersicon) fruit
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Harlequin bug (Hemiptera ) on honeysuckle (Lonicera)
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Harlequin bug (Hemiptera ) on honeysuckle (Lonicera)
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Juvenile green stink bug (Hemiptera ) on red maple (Acer)
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Harlequin bug nymphs (Hemiptera ) on spider flower (Cleome); note, damage to leaves
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Harlequin bug adult (Hemiptera ) on spider flower (Cleome)
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Harlequin bug nymphs on spider flower (Cleome); note, white flecks in the leaf typical of feeding by true bugs
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Despite appearances, this harlequin bug nymph (Hemiptera ) did not chew holes in the leaf of this spider flower (Cleome); it has piercing-sucking mouthparts, not mandibles
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Harlequin bugs (Hemiptera ) have sucked the life out of this spider flower (Cleome)
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The favorite food of harlequin bugs (Hemiptera ) is cabbage; shown here on cabbage's close relative broccoli (Brassica)