The Brown Marmorated Stink Bug (Halyomorpha halys) is the species most commonly encountered by homeowners, especially when seeking shelter indoors during cooler months. While these insects are a nuisance and agricultural pest, they are not generally poisonous or medically dangerous to humans or household pets. Concerns about their toxicity stem almost entirely from the strong, unpleasant odor they emit when they feel threatened or are crushed.
The Truth About Stink Bug Toxicity
Stink bugs are neither poisonous nor venomous as a threat to human health. An organism is venomous if it injects a toxin through a bite or a sting, and stink bugs possess no venom apparatus or stinger. They are not considered poisonous in the medical sense, as ingesting a single insect will not cause severe systemic toxicity. Stink bugs are primarily herbivores, utilizing a piercing-sucking mouthpart called a stylet to feed on plant juices, and they do not carry diseases transmissible to humans or pets.
What Is the Defensive “Stink” and Is It Harmful?
The “stink” is a chemical defense mechanism produced by glands on the underside of the thorax and abdomen, released as an odorous liquid. The main components are volatile organic compounds, specifically aldehydes like trans-2-octenal and trans-2-decenal. These compounds are low-toxicity but highly irritating and serve to repel predators.
While the secretion is not a potent poison, direct contact can cause adverse reactions in sensitive individuals. Skin exposure may result in mild, temporary irritation known as contact dermatitis. The most concerning reaction involves the eyes, where the aldehydes can cause severe chemical irritation or keratitis if the fluid is rubbed in. Mild allergic reactions are also possible, potentially leading to symptoms like a runny nose, sneezing, or itchy eyes. The odor itself is often described as smelling like cilantro or coriander.
Safe Handling and Accidental Ingestion
To prevent the release of the defensive odor, avoid crushing the insect. When removing them from a home, gently sweep them into a container or use a vacuum cleaner, ensuring the bag is immediately removed and discarded outside. Manual removal should be done with gloves to prevent skin contact with the irritating fluid.
If a child or pet accidentally ingests a stink bug, severe toxicity is highly unlikely. The foul taste of the aldehydes usually causes an immediate, strong aversion, which prevents consumption of multiple insects. Ingestion may cause mild gastrointestinal upset, such as vomiting, excessive drooling, or temporary mouth irritation due to the harsh chemicals. If eye contact with the fluid occurs, immediate and thorough rinsing with water is necessary, and medical attention should be sought promptly. If persistent vomiting or signs of choking are present after ingestion, veterinary or medical consultation is advised.