Brown Marmorated Stink Bug

Chances are over the last few years your home has been invaded by smelly, brown, shield-shaped bugs like the one pictured above.

This unwelcome guest, the brown marmorated stink bug (Halyomorpha halys), or "stink bug" as they're commonly known, seems particularly adept at finding any and every entry into warm homes as the colder weather sets in. H. halys was introduced to North America from Asia in the late 1990s. Without their natural predators, stink bug populations have exploded, causing them to become both an agricultural and residential pest.

In the northern United States, H. halys has one generation each year. However, up to five generations occur each year in their native southern China, and the same is likely in the U.S. as they move further south to warmer climates. Stink bug eggs are laid in clusters of around 25 eggs on the underside of leaves. The young stink bugs (nymphs) then go through five nymphal instars, or growth stages, before reaching maturity (the adult phase). Adults seek shelter from colder temperatures in the fall, which is when they generally begin entering homes and other buildings.

Unfortunately, the brown marmorated stink bug is more than just a smelly nuisance. This invasive species is actually quite destructive, and can wreak havoc on a wide variety of crops and ornamentals. Fruit trees are particularly susceptible, but other affected plants include butterfly bush (Buddleia spp.), mulberry (Morus sp.), soybean (Glycine max) and flowers of hibiscus (Hibiscus rosa-sinensis). Stink bugs pose another vineyard-specific problem, as they can easily be accidentally harvested along with grape clusters, causing stink bug infused wine!

So what can be done to stop the invasion of our homes and the destruction of our food and drink? Stink bugs do have natural predators, including a tiny parasitic wasp from Asia now known as the samurai wasp (Trissolcus japonicus), which lays its eggs inside stink bug eggs. Researchers were once weighing whether to bring it to the U.S. on purpose, because introducing a new species can harm other, non-target insects and compete with native parasitic wasps. Then, in 2014, wild populations of the samurai wasp were found already living in the U.S., and it has since been found in many states, where researchers are studying how well it keeps stink bugs in check. Praying mantises, a native species, do eat stink bugs and are another option for natural, biological control.

There are also chemical controls which can be useful in controlling this particular pest. Pyrethroids provide fairly effective, though short term, control of H. halys, but unfortunately bring their own set of secondary pest problems, including mites (in orchards) and mealybugs (in vineyards). Some neonicotinoids such as clothianidin have been shown to be effective in the short term, though control studies are still underway as H. halys is a relatively new pest. As with any species, the stink bug will eventually build a resistance to any chemical control.

Lastly, mechanical exclusion is an effective method of controlling the number of pests that make it into your home. Stink bugs generally enter dwellings through small holes or cracks in and around windows, so securing these areas with quality silicone or silicone latex caulk can significantly reduce populations indoors. Also be sure to repair or replace any damaged screens on doors or windows.

As we continue to learn more about the brown marmorated stink bug, it is likely additional controls will become available. Until then, BioLogic's littlest dog Pogo is happy to hunt down and pounce upon any Halyomorpha halys that make it into our home!