The brown marmorated stink bug (BMSB) is a common household and agricultural nuisance across many regions. These shield-shaped insects are known for releasing an unpleasant odor when disturbed and are frequently observed in high numbers.
An Uninvited Guest: Their Arrival
The brown marmorated stink bug (Halyomorpha halys) originated in East Asia. Its introduction to North America and Europe is largely attributed to accidental transport, often as stowaways in shipping containers or cargo.
The first documented presence in the United States was in Pennsylvania in the mid-1990s. From this initial point, the species rapidly spread, establishing populations across many states. Its arrival in Europe is believed to have occurred around the same time.
Why They Thrive: Factors Behind Their Abundance
The significant increase in brown marmorated stink bug populations in non-native regions stems from several biological and environmental factors. A primary reason for their success is the absence of natural predators and parasites that regulate their numbers. In Asia, tiny parasitic wasps, such as the samurai wasp, are highly effective at attacking stink bug eggs. These natural enemies were not present when the stink bugs arrived, allowing populations to expand without significant biological control.
Brown marmorated stink bugs are highly adaptable and possess a remarkably broad diet. They feed on over 100 species of plants, including agricultural and ornamental crops. This extensive food source provides ample sustenance for large populations. Furthermore, these insects have a high reproductive rate; a single female can lay up to 400 eggs and they can produce multiple generations per year.
As temperatures cool in late summer and early autumn, adult stink bugs seek sheltered locations to overwinter. They often congregate on the outside of buildings and enter homes through small cracks. While inside, they enter a dormant state, their presence in large groups during these periods is noticeable.
The Problems They Pose
Large populations of brown marmorated stink bugs create significant issues for both agriculture and homeowners. In agricultural settings, they are considered a serious pest due to damage they inflict on various crops. They feed on fruits, vegetables, and field crops, using piercing-sucking mouthparts to extract juices. This feeding can cause cosmetic damage, leading to unmarketable produce and substantial economic losses for farmers.
Beyond agricultural damage, these insects are a considerable nuisance in residential areas. As they seek warmth, they invade homes and buildings in large numbers. While they do not bite humans or pets, transmit diseases, or cause structural damage, they release a strong, unpleasant odor when disturbed or crushed. This defensive mechanism can also stain surfaces.
Controlling Stink Bug Numbers
Managing brown marmorated stink bug populations involves both preventative measures and direct removal strategies. For homeowners, the most effective approach to prevent indoor infestations is to seal entry points into buildings. This includes caulking cracks around windows, doors, utility pipes, and vents, as well as repairing damaged screens. Removing debris and vegetation near the home’s foundation can also reduce their attraction to the area.
For stink bugs that have already entered a home, physical removal methods are recommended. These can include using a vacuum cleaner to collect them. Another effective and inexpensive method is to create a light trap: a foil pan filled with soapy water placed under a light source will attract the bugs, causing them to fall into the water and drown. Chemical pesticides are generally not recommended for indoor use due to limited effectiveness and potential odors.
Broader control efforts, particularly in agriculture, often involve integrated pest management (IPM) approaches, which combine various strategies. Research is also ongoing into biological control methods, focusing on the potential introduction and establishment of natural enemies, like the samurai wasp. These tiny wasps, which parasitize stink bug eggs, offer a long-term, environmentally sound solution to restore ecological balance.