Stink Bugs Out of Dormancy

Late May in our area has warmed bringing out Brown Marmorated Sting Bugs (Halyomorpha halys) in full force after their winter dormant period. 2010 has been the most prolific year so far for these invasives from Asia. Estimates are that the overwintering adult population is more than 50% larger this year, which could bring increased numbers in comparison with 2012. On the bright side, nature in our area is adapting to these pests, and many species of animals are finding them edible. After gathering in sheltered locations in the fall, stink bugs overwinter in a dormant state, emerging in the spring to feed and then lay eggs. In Asia, up to 4 life-cycles have been observed per year, while in the US the insects commonly have one life-cycle per year. In warmer parts of the mid-Atlantic region, a second life-cycle is occasionally being observed, with the stink bugs being prevalent at different times throughout the year. In our area the adults emerge from dormancy and begin feeding in mid-spring on a wide range of fruits, vegetables, and other host plants including soybeans. They mate about 2 weeks after emerging from dormancy, with the females laying white or pale green, barrel-shaped eggs about 1 mm in diameter on the undersides of leaves in groups of about 2 dozen. Females will lay a total of about 400 eggs over a several month period, causing the nymphs to emerge throughout the summer. The first stage of nymph hatches in about 5 days, growing to adult size in about a month. The nymphs feed through the summer and seek shelter in the October-November time frame. They are most often seen on houses in the spring, as they emerge from dormancy, and in the fall, as they seek protected spaces to overwinter.

Credit: - Gary Bernon, USDA

Adults are approximately one half inch in length with a dark-brown, shield-shaped body and white bands on legs and antennae. The white bands on the antennae are the most distinguishing feature from other stink bugs. The stink bug uses a proboscis to penetrate plants and fruits to feed. As a result, the surface of fruits and plants it feeds on becomes dimpled and rough, degrading the quality of the fruit and possibly transmitting other plant diseases. Stink bugs get their name from the strong odor they release from stink glands located on the underside of the thorax (between the first and second pair of legs) and on the dorsal surface of the abdomen. The stink bug's ability to emit an odor through holes in its abdomen is a defense mechanism meant to prevent it from being eaten by birds and lizards. However, simply handling the bug, injuring it, or attempting to move it can trigger it to release the odor.

The life span of a stink bug is about 2 years, with die-off in the second year after reproduction. However, many over-wintering in homes low winter humidity will dehydrate leaving deposits of stink bug bodies in secluded places. Since first identified in Pennsylvania in 2001, the stink bug has proliferated, and natural predators and parasites have been adapting to help control them. The University of Maryland Extension reports that parasites are attacking the eggs, native birds are feeding on stink bugs, and domestic poultry is finding them to be an easy food source. On the bright side, the Brown Marmorated Stink Bug does not bite and is not directly harmful to humans.

Article by FCFCDB

Nature Notes for 6/2/2013