Stink Bugs
Green stink bug, Acrosternum hilare (Say)
Brown stink bug, Euschistus servus (Say)
Southern green stink bug, Nezara viridula (Linnaeus)
Pentatomidae, HEMIPTERA


DESCRIPTION (several species)

Adult - All adult stink bugs are shield-shaped. Green and southern green stink bugs are bright green and measure 14.0 to 19.0 mm long. The major body regions of the green stink bug are bordered by a narrow, orange-yellow line. Brown stink bugs are dull brownish-yellow in color and 12.0 to 15.0 mm long. Color plate.

Egg - When first laid, the barrel-shaped eggs of the green stink bug are yellow to green, later turning pink to gray. Eggs of the green stink bug measure 1.4 x 1.2 mm. The white, kettle-shaped eggs of the brown stink bug are slightly smaller than those of the green stink bug. The creamy, cylindrical eggs of the southern green stink bug measure 1.0 by 0.75 mm and develop a pinkish hue before hatching.

Nymph - The nymphs of all three species are smaller than adults, but similar in shape. Green stink bug nymphs are predominantly black when small, but as they mature, they become green with orange and black markings. Nymphs of the brown and southern green species are light green. Southern green stink bug nymphs, however, have two series of white spots along their backs. Color plate.


BIOLOGY

Distribution - Brown and green stink bugs have been reported as far north as Quebec. In the United States, however, they are more often injurious in the South. Although the southern green stink bug occurs outside the United States, in this country it occurs only from Texas to the Atlantic coast and northward to Virginia. It is an important pest in the Gulf Coast states. In North Carolina, however, the green stink bug is the predominant species.

Host Plants - Stink bugs feed on over 52 plants, including native and ornamental trees, shrubs, vines, weeds, and many cultivated crops. The preferred hosts are nearly all wild plants. Stink bugs build up on these hosts and move to soybeans late in the season as their preferred foods mature.

Damage - Stink bugs inflict mechanical injury to the seed as well as transmit the yeast-spot disease organism. The degree of damage caused by this pest depends to some extent on the developmental stage of the seed when it is pierced by the stink bug's needlelike mouthparts. The younger the seed when damaged, the greater the yield reduction. Although late season infestations may not affect yield, bean oil content and germination will be reduced.

Life History - Stink bugs overwinter as adults and become active in spring when temperatures rise above 21 degrees Centigrade (above 70 degrees F). Each female deposits up to several hundred eggs, usually in mid- or late June. These eggs are laid in clusters (averaging 36 eggs) primarily on leaves and stems but also on pods. Nymphs hatch from these eggs and pass through five instars before becoming adults. Approximately 5 weeks elapse between hatching and adult emergence. Two generations per year occur in Arkansas while only one generation per year has been reported in Virginia. In any case, stink bugs generally reach high population levels in late September or early October. It is then that stink bugs may become a problem on soybeans.


CONTROL

Stink bugs have some natural enemies, including several common species of birds. As their name implies, stink bugs emit an unpleasant odor and repel many predators. To determine when chemical control is necessary, shake the plants on about 1 meter (3 feet) of row over a muslin cloth and count the number of stink bugs. The economic threshold varies from 1 stink bug per 0.3 meter (1 ft) of row to 1 bug per 0.9 meter (3 ft) of row, depending upon state extension service recommendations. In North Carolina, the first threshold value applies. For additional information and current control recommendations, consult the current North Carolina Agricultural Chemicals Manual.