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What Is a Brown Marmorated Stink Bug?

Updated Mar 14, 2023

Updated Mar 14, 2023

Home > Pest > What Is a Brown Marmorated Stink Bug?

Few pests hold the same infamy as stink bugs. These odorous home invaders seem to swarm in the thousands every year, infesting homes and devastating crops. Present in just about every part of the U.S., almost no homeowner is spared their foul presence. While stink bugs are a nuisance throughout the year, they become a pervasive problem as seasons change and temperatures cool. This article will look closely at this annoying bug and discuss how you can best keep them out of your home during fall.

What Are Brown Marmorated Stink Bugs?

The brown marmorated stink bug (BMSB), or Halyomorpha halys (Stål), is a true bug (order Hemiptera) from the Pentatomidae family. It originated in Eastern Asia, specifically Japan, China, Taiwan, and the Koreas, but was accidentally introduced to the United States in the late 1990s. Its first introduction to the states is suspected to originate in Allentown, Pennsylvania. However, experts suspect that it had existed in the region for several years before its initial spotting in Allentown.

Today, the BMSB is a highly invasive species spreading like a reeking wildfire and can be found throughout North America. While most common in mid-Atlantic states, these pests can also be found in large numbers as far down as Alabama and along the West Coast in states like Oregon.


stink bug up-close
Image Source: Canva

The odds are good that you’ve encountered a BMSB, as it’s one of the most common stink bug species in the U.S. It has a small shield-shaped body, measuring about half an inch in length (17 millimeters) and the same in width. Its colors range from multiple shades of mottled brown to off-gray and beige. It resembles other stink bug species, like the equally common brown stink bug (Euschistus servus). Its name, marmorated (meaning veined or streaked), comes from the distinct white bands on its antennae and stripes along the ridge of its body. It also possesses a darker overlapping portion of its wings (the tip of the shield, located at its rear end).

Life Cycle

stink bug eggs on a leaf
Image Source: Canva

BMSBs have one to two generations per year, depending on environmental factors. Adults will emerge in late spring, reproducing and laying eggs in mid to late summer. The eggs are small, at just over half an inch wide (1.7 millimeters), with an elliptical shape, and are light green when laid. Eggs are laid in close clusters of 20 to 30 on the underside of leaves. As the stink bugs hatch, they go through five distinct stages called instars, beginning as nymphs and progressing to adults over 40 to 60 days. After hatching, in their first instar, stink bug nymphs possess black, red, and yellow abdomens with red eyes. As they mature, their colors become less vibrant, softening to a gray-brown or off-white with red or yellow spots and eventually transitioning to the mottled, adult brown coloration. 

Why Are Stink Bugs Pests?

Stink bugs are considered a nuisance and agricultural pest, as they’re annoying home invaders that cause significant damage to various crops.

Household Nuisance Pests

For homeowners, stink bugs search for overwintering sites or locations to stay warm during fall. As a result, stink bugs are attracted to the warmth human dwellings provide, often clinging to siding or resting near doors and windows. They’ll seek out any available entry point, slipping through small cracks in foundations or crawling through holes in window and door screens. Once inside, they’ll hide anywhere, like furniture, bookcases, baseboards, countertops, and beds. While they don’t bite, transmit diseases, or cause structural damage, they give off a foul odor when disturbed.

Some individuals have an adverse reaction to the odor and liquids produced by stink bugs. When exposed to a stink bug’s odor, sensitive individuals may experience rhinitis or conjunctivitis (nose and eye irritation). If a stink bug’s liquids are exposed to the skin, usually due to smashing, it can cause dermatitis (skin irritation or minor rash).

The biggest issue homeowners face when dealing with stink bugs is their numbers. While some regions may only experience a few dozen stink bugs during fall, home invasions numbering in the hundreds to thousands have been reported in deeply affected areas.

A Serious Agricultural Pest

The brown marmorated stink bug is considered a major agricultural pest, feeding on over 100 different species of host plant. They’ll damage tree fruits, including apples, pairs, apricots, peaches, citrus fruits, cherries, and nectarines. For field crops, they destroy beans, sweet corn, pepper, soybeans, eggplant, okra, squash, and much more. They’re also known to drain the juices from leaves, causing damage to ornamental plants.

Stink bugs harm fruit and vegetable crops by using a long, sucking mouthpart called a stylet. They penetrate developing plants and seeds, draining the juices. Damage from the BMSB is not immediately evident and varies depending on the type of plant being fed upon. Apples, for example, develop indents of necrotic tissue and are referred to as “cat facing,” becoming no longer fit to sell. Beans and corn are known to become shriveled, have sunken areas, and develop deformed pods or kernels. Peaches, peppers, and tomatoes develop pulpy, spongey internal sections, resulting in tissue damage and rot.

stink bug damaged tomatoes
Image Source: Canva

How Do You Prevent Stink Bugs?

While some pesticides and insecticides effectively prevent stink bugs, they’re generally discouraged. Pesticides will only delay stink bug problems and damage beneficial outdoor insects. The best method of keeping stink bugs away is “mechanical exclusion” or sealing all possible access points. Stink bugs find their way inside homes through small cracks, crevices, and gaps in your foundation, siding, walls, and window frames. We recommend a yearly home inspection and repair during late summer before stink bugs begin looking for overwintering locations during early fall.

The most important locations on your summer stink bug prevention checklist are:

  • Window and doorframes: Small cracks and gaps in window and doorframes provide more than enough space for pests to sneak through.
  • Foundation cracks: Cracks or crevices in your home’s foundation are a problem for multiple reasons, not just because they let stink bugs inside. Cracks can fill with water and freeze during winter, resulting in serious damage. We recommend promptly filling any crack with a good silicone sealant or outdoor-rated silicone caulk.
  • Weather stripping: Another common pest entry point is old and worn-down weather stripping. You should check your weather stripping along doors and windows at least once every two to three years.
  • The bottoms of doors: If you have a door that has a gap between its base and the floor, adding a door sweep will keep pets, and drafts, out.
  • Vents, pipes, and utility lines: We recommend carefully checking for gaps around pipes and utility lines and filling them with silicone caulk. For dryer vents, fill outside gaps with caulk or install a cap, grill guard, or mesh screen cover.

How Do You Get Rid of Stink Bugs?

caulking a window frame
Image Source: Canva

Once inside, removing stink bugs can be a pain, especially in large numbers. We don’t recommend smashing them, as this will release large amounts of their foul, agitating odor. You can easily vacuum and dispose of them, but your vacuum will smell for some time afterward. Glue traps and DIY dish soap traps are known to be effective but can result in the stink bugs releasing their smell. If experienced in small numbers, knocking them into a small bowl of water and dish soap can allow you to collect them without an odorous reaction. But if you’re dealing with a full infestation, insecticidal sprays are not recommended inside your home, and your best bet is to contact a pest control company.

On a commercial level, the U.S. Department of Agriculture (USDA) has developed several methods that allow fruit and vegetable growers to control stink bugs en masse. Traditional chemical control methods combined with pheromone lures have shown to be effective. Agricultural control scientists have also been experimenting with introducing parasitoid wasps like the Asian samurai wasp (Trissolcus japonicus).

Final Thoughts

The brown marmorated stink bug has a well-deserved reputation as one of the world’s most bothersome and invasive pests. These little, reeking insects will take advantage of any opening in your home’s defenses to get inside. They invade homes, damage crops, and are difficult to remove and exterminate.

By undertaking regular maintenance practices, you can ensure your home is pest-free all year round. Unfortunately, even well-maintained homes can still suffer from large amounts of stink bugs. In these situations, contacting a pest management company for regular spraying will provide relief.

Currently, the USDA is tracking the brown marmorated stink bug and developing numerous means of biological control and chemical responses. If you want to know more about this pest or report a BMSB sighting, you can check out its official page at www.invasivespeciesinfo.gov.

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