Brown Marmorated Stink Bug

Halyomorpha halys is one of about 5,000 species of shield bug (family Pentatomidae) and easily the most economically destructive in North America. Native to East Asia (China, Japan, Korea, Taiwan), the species was first detected in Allentown, Pennsylvania in 1996 and has since spread to 47 US states and 4 Canadian provinces. As a polyphagous feeder, H. halys attacks more than 170 host plant species, including apples (especially severe), peaches, pears, raspberries, soybeans, corn, and ornamentals. She feeds by inserting her stylet through the fruit skin and injecting digestive enzymes that cause characteristic 'cat-facing' (depressed, corky tissue) on apples and similar damage on stone fruit. USDA estimates direct losses to US specialty crops exceed $37 million per year. The 'stink' is a defensive strategy: when threatened, the bug releases trans-2-decenal and trans-2-octenal from thoracic glands — these compounds smell strongly of cilantro mixed with rotten almonds, and they persist on skin and surfaces for hours. In autumn, adult H. halys aggregates by the thousands in buildings (attics, wall voids, behind siding), seeking sheltered overwintering sites. They do not reproduce indoors and do not feed in winter, but the sheer numbers and the smell when crushed make them a major nuisance pest.