Brown Marmorated Stink Bug
Halyomorpha halys (Note: This is an insect, specifically a true bug, not a spider)
Family Pentatomidae (Stink Bugs), Order Hemiptera (True Bugs)
Physical Description
Shield-shaped body typical of true bugs, featuring a broad abdomen, segmented antennae, and piercing-sucking mouthparts tucked beneath the body. It lacks the two body segments, eight legs, and chelicerae characteristic of spiders.
Size Estimate
Approximately 12 to 17 millimeters (0.5 to 0.7 inches) in length, standard adult size.
Coloration & Markings
Mottled brown and grayish coloration with alternate dark and light bands along the outer edge of the abdomen (connexivum). Pale bands are typically visible on the final segments of the antennae.
Web Type
Does not build webs. This is a terrestrial and arboreal insect.
Eye Arrangement
Two compound eyes located on the sides of the head, supplemented by two simple ocelli, differing entirely from spider eye arrangements.
Leg Characteristics
Six legs with standard insect segmentation, lacking the specialized tarsal claws and silk-spinning spinnerets of spiders.
Venom & Safety Information
Venom Information
Non-venomous. It possesses no venom apparatus, fangs, or capability to bite humans in a medically significant way.
Medical Significance
Harmless to humans and pets. It does not bite, sting, or transmit diseases. The primary nuisance is the foul odor it emits and its tendency to aggregate inside homes in large numbers.
Safety Recommendations
Do not squash them to avoid releasing the foul odor. Gently pick them up using a tissue or trap them in a container to release them outside, or use a vacuum cleaner (though the vacuum bag may retain the odor temporarily).
Habitat & Behavior
Habitat & Range
Native to East Asia (China, Japan, Korea), but widely introduced and invasive in North America and parts of Europe. Found in agricultural fields, orchards, gardens, and invading homes in autumn to overwinter.
Behavior & Temperament
Docile when undisturbed, but releases a foul-smelling chemical odor from abdominal glands when handled or threatened. Active during the warmer months and seeks shelter indoors during cold weather.
Diet & Prey
Herbivorous. Uses piercing-sucking mouthparts to feed on plant sap, fruits, and seeds from a wide variety of agricultural crops and ornamental plants.
Seasonal Activity
Active during spring and summer feeding and reproducing outdoors. Adults become a common household nuisance in autumn as they seek warm indoor spaces to enter diapause (overwintering).
Description
Although submitted under the assumption of being a spider, this organism is actually the Brown Marmorated Stink Bug, a common agricultural pest and household invader. Recognized by its distinct shield-like shape and mottled brown camouflage, it is famous for the pungent odor it releases when disturbed. While harmless to humans, it can be a significant nuisance when it enters homes by the hundreds to overwinter.
Key Features
Shield-shaped body, mottled brown coloration, banded antennae, alternating dark and light markings along the abdominal edges, and six legs (identifying it as an insect rather than an arachnid).
Similar Species
Native brown stink bugs such as Euschistus species (Brown Stink Bug) and various squash bugs, which can be distinguished by subtle variations in antennal banding and abdominal edge patterns.
Life Cycle
Females lay clusters of pale, barrel-shaped eggs on the undersides of leaves. Nymphs go through five distinct instars before reaching the winged adult stage, completing one to several generations per year depending on climate.
Ecological Importance
Serves as an herbivore in its native and introduced ranges, often viewed negatively due to its status as an invasive agricultural pest that damages fruit crops and vegetables.
Conservation Status
Not applicable for conservation; considered an invasive agricultural pest in North America and Europe with robust and expanding populations.
Interesting Facts
When crushed or handled roughly, they release trans-2-decenal and trans-2-octenal, chemicals that produce a pungent odor resembling cilantro or pungent herbs, which serves as a deterrent to predators.
Photography Tips
Photograph from a top-down macro perspective to clearly capture the shield shape, antennal banding, and the distinctive pattern along the margin of the abdomen.
Identified: 2026-10-12T17:00:43.912021