Brown marmorated stink bugs are well established across New York State, particularly in the Hudson Valley, metropolitan New York City, and Long Island. Originally from Asia, these shield-shaped insects are harmless to people but become a major nuisance every fall when they push into homes by the dozens (or hundreds) looking for a warm place to spend the winter.
How Stink Bugs Arrived in New York
The brown marmorated stink bug was first officially documented in the United States from specimens collected in Allentown, Pennsylvania in the mid-1990s, though it wasn’t formally identified until 2001 by Cornell University entomologist Rick Hoebecke. Specimens collected in New York City were confirmed in 2007, and by 2008 the species had spread into the mid-Hudson Valley region. Since 2010, both the population size and geographic range in New York have been steadily increasing based on field trapping and reported sightings.
The Hudson Valley, metro NYC, and Long Island remain the leading edge of the population expansion. But stink bugs have been reported in counties across the state, and their range continues to grow. New York also has native stink bug species, but the brown marmorated variety is the one most likely to show up inside your house in large numbers.
How to Identify Them
Adult brown marmorated stink bugs are roughly the size of a dime, about 12 to 17 millimeters long, with a mottled brown, shield-shaped body. The easiest way to distinguish them from native stink bugs is the alternating light and dark bands on their antennae and along the outer edge of the abdomen. Native brown stink bugs lack these banded markings and tend to be a more uniform color.
The younger nymphs look quite different from adults. The smallest ones are black with yellowish-red markings on the abdomen. As they grow through five stages, they develop a pattern of rectangular spots on their backs and increasingly visible white dots along the edges of the abdomen. By the final nymph stage, they’re about 12 millimeters long and starting to resemble the adult form.
Why They Invade Homes in Fall
Stink bugs spend the summer outdoors feeding on plants and reproducing. As temperatures drop in late September and October, they begin searching for sheltered spots to overwinter, a behavior called diapause. Your home, with its warm walls and small entry points, is exactly what they’re looking for. They don’t eat, breed, or cause structural damage once inside. They’re just waiting out the cold.
Once they find a way in, they typically tuck themselves into wall voids, attics, and gaps around window frames. You may not notice them until a warm sunny day in late winter or early spring, when rising temperatures trick them into thinking it’s time to head back outside. That’s when they start appearing on walls, ceilings, and windows inside the house, sometimes in startling numbers.
Are Stink Bugs Harmful?
Stink bugs do not bite, sting, or carry diseases. They aren’t poisonous or venomous to people or pets. Their only real defense is the foul-smelling chemical they release when threatened or crushed, which is how they got their name. Some people experience mild skin irritation or minor respiratory symptoms from the secretions, but allergic reactions are rare.
If your cat or dog eats one, expect some temporary drooling, vomiting, or stomach upset from the bitter defensive chemicals. Severe reactions are uncommon unless a pet manages to eat a large number of them, which could theoretically cause a digestive blockage. In general, the bugs are passive and not aggressive toward people or animals.
For New York’s agricultural sector, stink bugs are a more serious concern. They feed on apples, pears, peaches, soybeans, and other crops by piercing the skin of fruit and injecting saliva, leaving behind dimpled, discolored spots that make produce unsellable. This is particularly relevant in the Hudson Valley’s apple and stone fruit orchards.
Keeping Stink Bugs Out of Your Home
Physical exclusion is the most effective long-term strategy. Stink bugs enter through surprisingly small gaps, so a thorough inspection of your home’s exterior before fall is worth the effort. Focus on these entry points:
- Windows and doors: Replace worn weatherstripping and repair or install tight-fitting screens. Check for gaps where window air conditioning units were removed.
- Foundation cracks: Seal any visible cracks with exterior-grade caulk, paying attention to where utility pipes and wires enter the house.
- Soffits and roof vents: Make sure attic vents have intact screening, and check where the roofline meets the siding for gaps.
The goal is to button up the exterior before stink bugs start their fall migration indoors, ideally by mid-September in most of New York. Once they’re already inside wall voids, sealing exterior gaps won’t help with the bugs already there, but it will reduce next year’s invasion.
Removing Stink Bugs Already Inside
The cardinal rule: don’t squash them. Crushing a stink bug releases the pungent odor that can linger on surfaces and hands. Instead, pick them up gently using a plastic bag turned inside out like a glove, then seal the bag and dispose of it outside. You can also drop individual bugs into a jar of soapy water, which kills them quickly without triggering the smell.
If you’re dealing with larger numbers, a vacuum cleaner with a disposable bag works well. Vacuum up the bugs, then immediately remove the bag and take it to an outdoor trash bin. Using a bagless vacuum is a mistake you’ll only make once, as the smell can persist inside the canister.
For a passive approach, a simple light trap works overnight. Fill an aluminum roasting pan with water and a few drops of dish soap, then position a desk lamp so it shines into the pan. Leave it in a dark room. Stink bugs are drawn to the light, fall into the soapy water, and drown. This won’t eliminate an infestation, but it can catch a surprising number over several nights.
Natural Predators in New York
One reason brown marmorated stink bugs became such a problem in the U.S. is that they arrived without the natural enemies that keep their populations in check in Asia. That’s slowly changing. A tiny parasitic wasp called the samurai wasp, originally from the same region as the stink bug, has established itself across much of the northeastern United States, including New York. The wasp lays its eggs inside stink bug eggs, destroying them before they hatch.
The samurai wasp is now found in both rural and urban areas wherever stink bugs are present. It’s too small to sting people and poses no risk to other insects’ populations. Researchers at Cornell recommend conserving these wasps rather than attempting to release them, since they’re already spreading naturally and finding stink bug egg masses on their own in gardens, farms, and landscaped areas. While the wasp won’t eliminate stink bugs entirely, it’s expected to gradually reduce their numbers over time.