Ruud Kleinpaste
A tiny bug that’s causing a big stink
you may have seen the notices and advertisements in your favourite magazine by our very own Ministry for Primary Industries (MPI). They concern the arrival and detection of a curious exotic insect with a weird name: the brown marmorated stink bug ( Halyomorpha halys).
Entomologists, who love to use FLAs (Four Letter Acronyms), refer to it as BMSB. MPI has been harping on about this bug for a while now, so I thought it was time to have a good look at this critter that threatens to migrate to Aotearoa.
The species originates in Asia (notably China, Korea and Japan) and has been on the move since the mid-1990s. It soon reached America, where it has caused not just a great deal of alarm, but also a huge amount of damage to stone fruit (like peaches and nectarines), pip fruit (apples, pears, nashi), assorted varieties of berries (including grapes, kiwifruit, blueberries, raspberries) and the vegetables we’re so familiar with – tomatoes, sweetcorn and peppers. You name it, the list goes on.
A huge amount of damage? How does a conservative estimate of US$20 billion dollars per year sound?
So here we have a true stink bug (family Pentatomidae) that looks like a brown version of our wellknown green vegetable bug. It is, however, a bit larger in size, and mid-brown with distinct black and white markings on its abdomen and white banding on its antennae.
Although it may superficially look like some of our brown soldier bugs or brown shield bugs, the BMSB is about twice their size and much more numerous on tree crops and vegetables.
Keep a sharp eye out for this exotic threat: early detection gives us a chance to get rid of it before it sticks its proboscis into everything we value
These beasts have been intercepted quite a few times now, on machinery and used cars from the US, in international mail, and with passengers carrying camping material or just ordinary luggage. The BMSB is an ace when it comes to playing the stowaway, and MPI is doing its darndest to keep it out of our country.
Of course, you and I (gardeners and nature nerds) are the eyes and noses of biosecurity; we’re often outside, looking at plant crops and trees. So I think it’s absolutely crucial to keep a sharp eye out for this exotic threat: early detection gives us a chance to get rid of it before it sticks its proboscis into everything we value.
These super suckers ‘sting’ fruit, causing brown discolourations, corky patches on pip fruit and sunken lesions. They really know how to spoil vegetables and fruit, which sometimes wind up not even worth juicing.
The very act of inserting a proboscis full of saliva into plant material also allows transmission of fungal and bacterial diseases and disorders, further debilitating plants and crops. And on top of all that: the adult bug is just about immune (resistant) to any of the heavy-duty residual insecticides you would choose to use.
This species is extremely hard to control or kill. Organic methods or integrated pest management are likely to be almost completely ineffective, judging from recent research in the US. The BMSB sounds like an absolute disaster. It also smells like one: believe me, the green vegetable bug with its chemical version of coriander is decidedly pleasant to have around compared to the BMSB. Our interloper smells like sweaty socks on steroids. Curiously, you might expect this smell to be helpful as a kind of pheromone to trap the brutes, but that has proven to be a big challenge too. So far, not good. If you’re still not convinced that this BMSB is a bugger, you need to know about its hibernation strategy. It makes the cluster fly look like an amateur. These stink bugs have a habit of aggregating in huge numbers under bark or in other nooks and crannies. We’re talking thousands at a time. Your home, attic, shed, front porch and other sheltered areas are all suitable spaces for the bugs to get together and spend the winter months. It certainly explains why these insects are such good stowaways. All you can do is don a mask and broom the blighters out – remember: insecticides are basically useless. So please, have a look at the MPI website (mpi.govt.nz), keep an eye out for these serious suckers, and ring 0800 80 99 66 if you spot one in your garden.