Brown marmorated stink bug is a serious horticultural pest native to East Asia. It damages crops, infests ornamental plants, and seeks out shelter over the winter causing massive problems for homes and businesses. Fortunately we don’t have it in New Zealand yet, but in order to keep it out we need to know what it looks like. In this post I show you how to tell it apart from other New Zealand stink bugs.
First an important reminder: If you believe you may have found BMSB the best thing to do is to catch the bug, keep it alive, and call MPI on 0800 80 99 66.
When entomologists talk about ‘bugs,’ generally they mean the Hemiptera, a group of insects that share sucking mouthparts. Within the Hemiptera, stink bugs are members of the family Pentatomidae. Stink bugs are not beetles, they are ‘true bugs.’
In New Zealand we have 8 species of stink bug:
1. Cermatulus nasalis (made up of three subspecies)
Brown soldier bug – Cermatulus nasalis nasalis
Alpine brown soldier bug – Cermatulus nasalis hudsoni
Three Kings soldier bug – Cermatulus nasalis turbotti
2. Schellenberg’s soldier bug – Oechalia schellenbergii
3. Brown shield bug – Dictyotus caenosus
4. Pittosporum shield bug – Monteithiella humeralis
5. Alpine shield bug – Hypsithocus hudsonae
6. Green vegetable bug – Nezara viridula
7. Australasian green shield bug – Glaucias amyoti
8. Green potato bug – Cuspicona simplex
First up, lets have a look at BMSB:
Brown marmorated stink bug adult. Note the white banding on the both the legs and antennae, the stripes around the abdominal margin, and the ‘marmorated’ or marbled colouration. Image courtesy Kiwifruit Vine Health.
Two New Zealand species look similar to brown marmorated stink bug. These are Cermatulus nasalis and Dictyotus caenosus.
Brown soldier bug (Cermatulus nasalis nasalis), native to New Zealand but also present in Australia and Timor. A predator of other insects, especially the larval stages of moths and butterflies (caterpillars). Image © Landcare Research (CC-BY 4.0)
Brown shield bug (Dictyotus caenosus), introduced from Australia. Usually seen feeding on plantain grass or lucerne. Image © Landcare Research (CC-BY 4.0)
The key characters to look for when separating these two species from BMSB are a combination of size, banding and colouration.
Here is a side by side comparison of BMSB (on the left) with Cermatulus nasalis:
This species is the one most likely to be confused with BMSB, and it’s no wonder when you try to compare them above.
The white banding present on the antennae of BMSB is the most obvious way to separate these species, but BMSB is also a little bit larger (19mm long vs 17mm), and coloured slightly differently to Cermatulus nasalis.
Here is a side by side comparison of BMSB (on the left) with Dictyotus caenosus:
Again, the white banding on the antennae can be used to immediately separate these species. But you can also see that Dictyotus caenosus has a more pronounced notch in the top of the head and behind the eyes, than BMSB. Dictyotus caenosus is also quite a bit smaller, normally around 10mm long.
These two species are the ones most likely to be confused with BMSB in New Zealand.
But remember: If you do find a stink bug and you’re not sure what it is, the best thing to do is to catch the bug, keep it alive, and call MPI on 0800 80 99 66. Better to be safe than sorry with BMSB.
I have found what looks like a stink bug. Same shape etc. I put it in a container last night and this morning it is dead. Where do I send it to have it identified. I live at Bannockburn in Central Otago.
Hi Lesley,
I’ve emailed you a reply to make sure you see it.
For others reading: The best thing to do if you find a suspicious looking stink bug is to catch it in a container and call MPI on their pest & disease hotline: 0800 80 99 66
They will instruct you what to do next, or they may send someone out to collect the sample.
Thanks for this great post. I found a brown stink bug on my raspberry plants. Thought to check if it was the BMSB. After reading this I think it is the brown stink bug and it has been chomping away on raspberry bud moth larvae (or whatever larvae burrow into the fruit). I had no idea there were predatory native stink bugs, would have killed it thinking it was a variant of green vegetable stink bug that ruin my tomatoes. A great find. There are freshly hatched eggs now too, hoping I can farm them to use on the loopers once berries finish.
Hi Romy,
Yes indeed, if the beast in question was feeding on another insect then it definitely isn’t the herbivorous BMSB. Glad to hear you found the guide useful! You might be interested in this post on NZ stink bug species: https://tomsaunders.co.nz/nz-stink-bugs/
Kind regards,
Tom
I found a brown bug in my house in Waihi and found your site extremely helpful with identification. Lukily wasnt a BMSB. I hate the green stingbugs anyway, and this one going to bug hell! Merry Xmas. Thnx again
Thanks for letting me know Barbara, glad you found my post helpful. Merry xmas and a happy new year to you and your family. Regards, Tom.
Hi found this bug green and brown underside brown top white band on each feeler. Thought I had better get it checked out. I live in Fairfield can’t. Cheers.
Hi Tony, does it look like any on this page? If you’re worried you’ve found a brown marmorated stink bug best to call MPI on 0800 80 99 66.
Hi Tom, The monarch caterpillars on our milkweed plants are being attacked by what may be the “Brown Soldier Bug”.
We live at 25 Horotane Valley Road. Horotane, Hillsborough, Christchurch. Phone 0275674044. Should we report to MPI??
Hi Rae, if you’re seeing a predatory stink bug attacking monarch caterpillars then it is indeed likely to be the Brown Soldier Bug. This species is already known to occur in NZ and is not considered a pest. BMSB feeds on plants so we can safely rule it out in this instance. However, if you’re ever unsure in the future, call MPI and follow their instructions.
Kind regards,
Tom