The brown marmorated stink bug (Halyomorpha halys) is a dreaded crop-ravaging pest from Asia that may also pose a threat to native plants.
Photo: Yerpo | CC BY 3.0
The brown marmorated stink bug is not difficult to identify, if all the following features are taken into account. If your bug is an adult (it has wing shields and wings covering its segmented abdomen, as shown above) look for the following. (Young bugs are illustrated further down the page.)
- The upper surface is mottled and speckled brown with no pronounced stripes.
- The head is blunt rather than tapering to a point.
- The antennae have at least one white band.
- The edges of the abdomen are strongly banded.
- There are no spines on the body.
Photo: Hectonichus | CC BY-SA 4.0
We do not provide advice about how to identify young marmorated stink bugs, but two images are provided here as an indication.
The bugs are striking when they are tiny (under 4 millimetres in length), with dark red eyes, spines and a complex pattern.
A very young bug. Photo: Hectonichus | CC BY-SA 4.0
This bug is one moult away from adult size. It has wing buds rather than full-sized wing shields covering most of the abdomen. Photo: Hectonichus | CC BY-SA 4.0
Adult bugs are 12-17 millimetres long (not counting the antennae).
Behaviour and location
These bugs inhabit vegetation and tree trunks. In autumn they enter buildings and vehicles seeking warm places to hibernate over winter, so they can also be found indoors. They are entering Australia with imported goods so they turn up in warehouses and stores.
Like other stink bugs they emit a pungent smell when harassed.
Eastern and south-western Australia have the best climate for their establishment.
Australia has many native stink bugs that share some of the features of this species, but never all of them. Three native species are shown here as examples.
The two-dots gum tree shield bug (Poecilometis parilis) is easy to tell from a marmorated stink bug by its pointed head, antennae without a white band, and abdomen with no banding on the edges.
Two-dots gum tree shield bug. Photo: James Niland | CC BY 2.0
The common gum tree shield bug (Poecilometis patruelis) is darker than a marmorated stink bug, with a striped head that isn’t as blunt, and an abdomen with spines on the edges rather than bands.
Common gum tree shield bug. Photo: Moonlight0551 | CC BY 2.0
The brown soldier bug (Cermatulus nasalis) looks a lot like the brown marmorated stink bug, but lacks any wide white band on the antennae. Of all the bugs found in Australia, it may come closest.
Brown soldier bug_Photo Jean and Fred | CC BY 2.0
Brown soldier bug. Photo: Steve Kerr | CC BY 4.0
The Australian government has produced a guide to identify brown marmorated stink bugs, illustrating a large range of native stink bugs.
Stink bugs are not dangerous to handle, unless you are unlucky enough to be allergic to the chemicals they release (aldehydes) when they feel threatened. To be on the safe side, you can pick one up while wearing gloves, then put it in a plastic bag or bottle and place it in the freezer to kill it. Alternatively, you can take a photo.
Who to tell
Think you’ve found brown marmorated stink bugs?
If you think you have found one, phone the Exotic Plant Pest Hotline: 1800 084 881. You will be put in touch with the Department of Primary Industries or Agriculture in your state or territory.
This crop-destroying bug from eastern Asia has Australia on high alert. It created a sensation when huge numbers began arriving on ships in December 2014. According to one government report, a ship arriving in Brisbane had inspectors ‘shocked to see hundreds of bugs marching and flying out of the hold as the ship’s ramp was lowered.’ That vessel was quickly shut again and directed out to sea so the bugs could be destroyed. Three ships coming later were ordered to leave Australia without unloading their cargo because the infestations, of ‘many hundreds and possibly thousands of bugs’, could not be contained, the government declaring the level of infestation to be ‘unprecedented for any species of hitchhiking pest.’ In 2018-2019 the bugs arrived on so many ships and planes they ‘stretched Australia’s border biosecurity system close to breaking point’. That said, these bugs have been stopped from establishing in Australia so far.
They are turning up inside shipping containers, packing crates, aircraft, machinery, cars and personal luggage. During the northern autumn they enter homes, offices and factories in large numbers to escape the winter cold, and this habit facilitates their travel around the world.
Native to East Asia, they became infamous for mass damage on farms after spreading to North America in the 1990s and Europe in 2007. More than 300 different crops are damaged, ranging from fruits to vegetables to nuts.
The bugs have a straw-like beak (a rostrum), with which they pierce plants, then inject digestive enzymes, before imbibing a meal. They pierce fruits, nuts, buds, stems and bark, and the outcome is one of injured, deformed or aborted fruits and nuts. If disturbed they emit a nasty smell, and this contributes to the annoyance they create when they enter homes.
Brown marmorated stink bugs on a peach. Image: Gary Bernon, USDA APHIS, Bugwood.org | CC BY 3.0
While crop damage is the paramount concern, this bug might become an environmental problem. Many plants attacked overseas have close relatives in Australia, including figs (Ficus species), ebonies (Diospyros species), elderberries (Sambucus australica, S. gaudichaudiana), citrus species (Citrus species), raspberries (Rubus species) and others (Cayratia, Celtis, Chionanthus, Cinnamomum, Clerodendrum, Hibiscus, Lythrum, Solanum, Sophora, Vigna, Vitex species).
Australia has four endangered species of native tomato (Solanum armourense, S. celatum, S. limitare, S. sulphureum), all with small distributions and small population sizes. If bug damage reduced their fruit output that would greatly worsen their plight.
The wide range of plants attacked overseas makes it inevitable that some genera confined to Australia will be attacked as well. A plant family that is targeted north of the equator, Sapindaceae, has endangered species in Australia, such as smooth tuckeroo (Cupaniopsis serrata), small-leaved tamarind (Diploglottis campbellii), and the Isis tamarind (Alectryon ramiflorus), known from fewer than 30 plants.
If the bugs establish in crops, farmers will increase use of pesticides, which will become another environmental cost.
The bugs could provide a benefit by reducing the seed output of some environmental weeds such as camphor laurel and privets.
There are many web pages about the marmorated stink bug.
- Australian Government: Brown marmorated stink bug.
- Australian Government: Seasonal measures for brown marmorated stink bug.
- University of Florida: Featured Creatures.