Stink Bugs

Overview

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 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. The brown marmorated stink bug (Halyomorpha halys) is an Asian species that was introduced into Allentown, Pennsylvania around 1996 from China or Japan. In 2015 it was found in 42 states including Missouri. 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.  

In late September into mid-October, brown marmorated stink bug adults seek protected areas for overwintering. They can gain access into homes through cracks and opening around windows, doors, siding, fascia boards, chimneys, attics, or window air conditioners where they overwinter in walls and other locations. In spring, they can be found in interior spaces as they look for ways to reach the outdoors. 

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, pyrethrin, or permethrin. 

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. 

Pesticide Disclaimer: 

Always follow the product's label and ensure the product is effective against stink bugs. Not following the pesticide label before usage is a violation of federal law.