Stink Bugs 101: What Are Stink Bugs?
by Alex Schnee | March 19, 2025 | Blog
If you’ve encountered shield-shaped insects that emit a foul odor when disturbed, you’re likely dealing with stink bugs. These distinctive pests have become increasingly common throughout the United States, particularly during fall months when they seek shelter indoors. While not typically harmful to humans, stink bugs can be a significant nuisance due to their unpleasant smell and tendency to invade homes in large numbers.
What are stink bugs?
Stink bugs belong to the family Pentatomidae, with the brown marmorated stink bug (Halyomorpha halys) being the most common household pest species in North America. This invasive species was accidentally introduced from Asia in the late 1990s and has since spread throughout most of the United States.
While they don’t bite humans or cause structural damage, they can be agricultural pests, damaging fruits, vegetables, and ornamental plants by piercing plant tissue and sucking out juices. They earned their name from the defensive mechanism that releases a distinctive unpleasant odor when they feel threatened or are crushed.
What do stink bugs look like?
Stink bugs have a distinctive shield-shaped body that measures about 1/2 to 3/4 inch long. The brown marmorated stink bug is mottled brownish-gray with light and dark bands on its antennae and alternating dark and light spots along the abdomen’s edge. Their bodies are flat on top but slightly rounded underneath, giving them a somewhat turtle-like appearance. They have six legs and two antennae with light-colored bands.
One of their most identifiable features is their triangular plate (scutellum) in the middle of their back. Nymphs look similar to adults but are smaller, more rounded, and often yellowish with reddish eyes.
Lifecycle of a stink bug
Stink bugs develop through incomplete metamorphosis with three life stages: egg, nymph, and adult. The cycle begins in spring when female stink bugs lay clusters of 20-30 small, barrel-shaped eggs on the undersides of leaves. These eggs are light green to white initially, becoming more transparent as they develop, with tiny spines around the edges.
Eggs hatch within 4-5 days, producing nymphs that go through five developmental stages (instars) before reaching adulthood. Each instar lasts about one week, with the nymph molting between stages and growing progressively larger.
Nymphs lack fully developed wings and reproductive organs but otherwise resemble small adults. Their coloration changes through developmental stages, typically starting yellowish and becoming more brown with each molt.
In favorable conditions, stink bugs can complete their development from egg to adult in about 4-6 weeks. Adults typically live for several months, with those born in late summer entering a dormant state called diapause to survive winter. Most species produce 1-2 generations annually in northern regions and up to 5 generations in southern climates, allowing populations to build quickly during warm seasons.
Are stink bugs dangerous?
Stink bugs pose no significant health risks to humans. They don’t bite, sting, or spread diseases, nor do they damage home structures or furnishings. Their primary impact is as a nuisance pest due to their unpleasant odor and tendency to invade homes in large numbers during fall and winter.
While not dangerous to humans, they can cause economic damage to agricultural crops and ornamental plants by feeding on fruits, vegetables, and seed pods.
Why do stink bugs stink?
Stink bugs produce their characteristic odor as a defense mechanism against predators. When threatened or crushed, they release chemicals called trans-2-decenal and trans-2-octenal from specialized glands located on their thorax. These compounds create a smell often described as similar to cilantro, burnt tires, or pungent herbs.
The odor is designed to deter predators and can also serve as an alarm pheromone that attracts other stink bugs to potential threats, which is why crushing them indoors can potentially attract more.
Are stink bugs worse in the winter?
Stink bugs don’t reproduce during winter, but they often become more noticeable indoors during colder months. As temperatures drop in fall, they begin seeking protected locations to overwinter in a state of dormancy called diapause. Homes and buildings provide ideal shelter with their warm, protected spaces.
They commonly enter through cracks, gaps around windows and doors, vents, and other openings. During warm winter days or when heated homes raise their body temperature, they may become temporarily active and visible indoors before returning to hiding places. This creates the impression of increased winter activity, though it’s actually just increased visibility of existing populations.
Are stink bugs harmful to pets?
Stink bugs generally pose minimal risk to pets. If your dog or cat catches and eats a stink bug, they might experience temporary discomfort due to the bug’s foul taste and odor, potentially causing drooling, gagging, or vomiting.
However, stink bugs are not toxic or poisonous to pets. The primary concern would be if a pet consumes a large number of stink bugs, which could potentially cause digestive upset or irritation. Otherwise, these encounters are usually more unpleasant than dangerous for curious pets.
How to know if you have a stink bug infestation
Several signs indicate a stink bug infestation in your home. The most obvious is sighting multiple live stink bugs, particularly around windows, door frames, and light fixtures. During fall, you might notice increased numbers of these pests on south and west-facing exterior walls as they warm themselves in the sun before seeking winter shelter. Their characteristic odor might be detectable even when the bugs aren’t visible, especially if they’ve been crushed or disturbed.
Make sure to check dark, undisturbed areas like attics, crawl spaces, and wall voids, where stink bugs commonly overwinter in groups. You may find them in curtains, behind picture frames, or inside light fixtures. Their presence is most noticeable on sunny winter days when the increased indoor temperature temporarily rouses them from dormancy. If you find just one or two, it likely indicates more are hiding nearby, as stink bugs tend to aggregate in favorable locations.
How to prevent a stink bug infestation
Preventing stink bugs from entering your home starts with sealing potential entry points. Inspect your home’s exterior for cracks and openings, particularly around windows, doors, siding, utility pipes, chimneys, and underneath fascia boards. Seal gaps with quality silicone or silicone-latex caulk and install weather stripping around doors and windows. Repair damaged screens on windows, doors, and vents.
Create a defensive barrier by treating the exterior perimeter of your home with appropriate insecticides in late summer before stink bugs begin seeking winter shelter. Focus on south and west-facing walls where the insects typically congregate.
You will also want to reduce outdoor lighting at night or switch to less attractive yellow bulbs to minimize drawing stink bugs to your home. Keep vegetation trimmed away from your home’s foundation to eliminate potential bridges for these pests. Consider using essential oil repellents like mint, catnip, or citrus around entry points as additional deterrents.
How to get rid of a stink bug infestation
Addressing a stink bug infestation requires a multi-faceted approach. For immediate relief from bugs you can see, avoid crushing them, which releases their defensive odor. Instead, vacuum them up using a vacuum with a bag that can be sealed and discarded after use. For smaller numbers, you can carefully collect them using a plastic bag or container and release them outdoors far from your home.
Create simple traps using a desk lamp shining into a pan of soapy water—the light attracts the bugs, and they drown in the water. Commercial stink bug traps using light, pheromones, or both can also be effective for reducing indoor populations. Various essential oils, including mint, neem, and clove oil, can serve as repellents when sprayed around entry points and windowsills.
H2: When to call a professional
If you’re seeing stink bugs around your windows or inside your home, don’t wait to take action. You’ll want to contact Pest Control Experts today for a free quote from our trusted pest control providers and get a customized treatment plan! Our experts will identify potential entry points and implement targeted control methods to protect your home from these odorous invaders before they establish large indoor populations.
