Key takeaways
- Stink bugs in the house are harmless to people. The brown marmorated stink bug (Halyomorpha halys) and native shield bugs feed on plants, not blood. They do not sting and practically never bite.
- They come indoors in September and October to find a dry, sheltered place to overwinter. They do not breed, eat food or damage the house.
- The smell is their only weapon. When crushed or disturbed they release a pungent, coriander-like odour, which can trigger rhinitis or itchy eyes in sensitive people.
- Evict, don’t squash. Catch them in a jar or a stocking-covered vacuum hose and seal gaps around windows, vents and cables before next autumn.
- Indoor insecticide sprays are not needed and do not stop new arrivals; exclusion is the method extension services recommend.
If a flat, shield-shaped brown bug has just landed on your lamp or curtain, you are probably looking at a stink bug looking for a winter home. Across Germany, Austria, Switzerland, Italy and much of Central Europe, the brown marmorated stink bug has become a familiar autumn houseguest. The good news: stink bugs indoors are a nuisance, not a danger. Here is how to identify them, why they arrive, and how to evict them without filling the room with their smell.
What is a stink bug?
Stink bugs, also called shield bugs, are true bugs (order Hemiptera) with piercing-sucking mouthparts designed for plant sap, fruit and seeds. Their name comes from defensive glands that release a strong-smelling liquid when they feel threatened.
The species most people find indoors is the brown marmorated stink bug (BMSB), known in German as the Marmorierte Baumwanze. It is native to East Asia and was spread around the world in shipping containers and goods. According to Penn State Extension, it was first collected in the United States in 1998. In Europe it has been recorded since the mid-2000s, first in Switzerland, and the European plant protection organisation EPPO tracks it as a significant pest of fruit and vegetable crops. The Royal Horticultural Society notes it is not yet proven to have colonised the UK, although individual bugs do arrive with travellers and imported goods.
How to recognise the brown marmorated stink bug
- Size and shape: about 17 mm long, shield-shaped and almost as wide as it is long.
- Colour: mottled (marmorated) grey-brown on top and underneath.
- Antennae: pale bands on the last segments.
- Edges of the body: alternating light and dark bands along the abdomen edge.
- Smell: the RHS describes it as resembling coriander.
Stink bugs you may confuse it with
| Bug | Size | Appearance | Comes indoors in autumn? | Risk to people |
|---|---|---|---|---|
| Brown marmorated stink bug (Halyomorpha halys) | About 17 mm | Mottled brown, banded antennae and body edge | Yes, often in large numbers | None beyond smell and possible allergy |
| Green shield bug (Palomena prasina) | 12–14 mm | Bright green in summer, turns bronze-brown before winter | Occasionally | None beyond smell |
| Southern green stink bug (Nezara viridula) | 12–15 mm | Green, sometimes with pale spots | Occasionally, mainly in southern Europe | None beyond smell |
| Western conifer seed bug (Leptoglossus occidentalis) | 15–20 mm | Longer, narrower, with leaf-like flattened hind legs | Yes | None; does not bite |
Why do stink bugs come into the house in autumn?
Adult brown marmorated stink bugs overwinter as adults. When days shorten and temperatures fall in September and October, they look for a dry, protected spot to wait out the cold. In their native range that means rock crevices and dead trees; in Europe, south- and west-facing house walls do the same job. Warm, sunlit facades attract them, and they squeeze through gaps around windows, roller-shutter boxes, vents, chimneys, siding and cable entries.
Once inside, most hide in loft spaces, wall cavities and behind curtains. Central heating can wake some of them on mild days, which is why you see single bugs crawling towards lamps and windows in November or even February. Penn State Extension confirms that stink bugs do not reproduce inside buildings or cause structural damage, and they do not eat food, clothes or furniture. In spring they try to leave again to feed and breed outdoors.
If you are seeing several kinds of insects moving inside at the same time, you are not alone: our guides to harlequin ladybirds indoors and autumn house spiders explain the other seasonal visitors.
Do stink bugs bite or sting?
No. Stink bugs have no sting, and their mouthparts are built to pierce plant tissue. They are not interested in human blood and are not known to transmit any disease to people. Very occasionally someone reports a pinprick when a bug probes the skin, but this is rare and harmless.
Can stink bugs cause allergies?
For most households the smell is the worst of it. However, Penn State Extension reports that the defensive chemicals can act as an aeroallergen, causing rhinitis or conjunctivitis in people who are sensitive to them, and that crushing the bugs can irritate the skin. People already sensitive to cockroaches or ladybirds may be more likely to react. If someone in your home gets a runny nose or itchy eyes every autumn that eases once the bugs are gone, mention it to your GP or an allergist.
What does a stink bug smell like and why?
When disturbed, crushed or sucked into a vacuum, stink bugs release a liquid from glands on their thorax. People describe the smell as coriander-like, grassy or slightly rancid. It is meant to deter birds and lizards, and it lingers on fingers, fabrics and vacuum cleaner bags. That is the main reason not to squash them.
How to get rid of stink bugs indoors (without chemicals)
- Catch single bugs in a jar. Place a glass over the bug, slide a piece of card underneath and release it outside, or tip it into a jar of soapy water if you have a large infestation and want to remove them.
- Use a stocking on the vacuum. Slip a thin stocking into the end of the hose and secure it with a rubber band. The bugs collect in the stocking, not the bag, so the cleaner does not end up smelling.
- Do not crush them. Squashing releases the strongest dose of odour and can stain light fabrics.
- Skip indoor insecticide sprays. They expose people and pets to chemicals, leave dead bugs behind in wall cavities and do not stop new arrivals. The US EPA’s integrated pest management principles favour prevention and physical methods first.
- Turn off unnecessary lights near windows on autumn evenings; stink bugs are drawn to light.
Prevention checklist for next autumn
- Seal cracks around window frames, doors, roller-shutter boxes, utility pipes and chimneys with silicone or silicone-latex caulk before early September.
- Repair torn fly screens and add fine mesh to vents and extractor fans.
- Check loft hatches and roof eaves for gaps.
- Shake out laundry dried outdoors and check garden furniture cushions before bringing them in.
- When returning from a holiday in a region with stink bugs, check suitcases and outdoor gear before unpacking.
Are stink bugs a problem in the garden?
For farmers and fruit growers, yes. The brown marmorated stink bug feeds on apples, pears, peaches, tomatoes, peppers, sweetcorn and many ornamentals, leaving dark, corky spots and distorted fruit. Italian pear and hazelnut growers have reported serious losses. In a home garden the damage is usually cosmetic, and native shield bugs are part of a healthy ecosystem. As we explain in which insects you should protect, most garden insects deserve a relaxed, chemical-free approach.
How incognito® helps
You do not need a repellent for stink bugs: they do not bite, and the solution indoors is sealing gaps and moving the bugs out. Autumn walks, gardening and mushroom foraging are a different story, because ticks and late-season mosquitoes are still active well into October — see what still bites in September and October. For those outdoor moments, incognito® Insect Repellent Spray is DEET-free and uses PMD (Citrepel®), a plant-based active derived from Java citronella. It is clinically proven, recommended against mosquitoes and ticks, vegan and biodegradable. You can browse the full incognito® range for family and travel options. Always follow the product label.
FAQs
Are stink bugs dangerous to humans?
No. Stink bugs do not sting, practically never bite and do not transmit diseases to people. Their only defence is a strong smell, which can irritate the eyes or nose of sensitive people.
Why do I suddenly have stink bugs in my house in October?
Brown marmorated stink bugs spend winter as adults and look for dry, sheltered places when temperatures drop. Sunny walls attract them and they slip in through gaps around windows, vents and shutters.
Will stink bugs lay eggs or breed in my home?
No. Stink bugs do not reproduce indoors. They stay dormant over winter and try to leave in spring to feed and breed outdoors on plants.
What is the best way to remove a stink bug without the smell?
Gently trap it under a glass and release it outside, or vacuum it into a stocking secured inside the hose. Avoid crushing it, which releases the strongest odour.
Can my dog or cat get sick from eating a stink bug?
Stink bugs are not poisonous, but their bitter taste can make pets drool or vomit. If your pet eats many of them or seems unwell, contact your vet.
Do stink bugs damage furniture or clothes?
No. They do not chew wood or fabric. The only damage is staining or a lingering smell if they are crushed on light fabrics or curtains.
Sources
- Penn State Extension — Brown Marmorated Stink Bug
- Royal Horticultural Society — Brown marmorated stink bug
- EPPO Global Database — Halyomorpha halys
- US EPA — Integrated Pest Management (IPM) Principles
- NHS — Insect bites and stings
This article is for general information only and does not replace medical or veterinary advice. If you have persistent allergy symptoms or a severe reaction, contact a doctor or pharmacist.