Know your wasp

The flying, yellow and black bullets of evil are everywhere it seems.  It pays to know what wasp is what, then you can deal to them. Number 8 Network takes a closer look at wasps – but not too close.

“We need to be savvy about wasps,” wasp killer extraordinaire Keith Holborow said on N8N back in 2014.

The retired engineer/teacher was volunteering at Pukemokemoke Reserve and his job was Wasp Destruction, the more the merrier.

This year too, has seen conditions clearly favouring wasps, and around here, at least, there have been swarms of Asian paper wasps.  They’ve been building up through the season, and have boomed in recent weeks.

So it’s a good idea to know what wasp is what and what to do with them and their plans of world domination.

What wasp is what
There are four species considered pests in the Waikato – the German wasp, the common wasp, the Asian paper wasp, and the Australian paper wasp.  All are accidental introductions.

Asian paper wasp (Polistes chinensis)
These guys are smaller and thinner looking than the German and common wasps, from 13 to 25mm long. They are yellow and black and have long legs which dangle beneath their bodies during flight.   For most of the year only females are seen, but in the autumn (i.e. now) males appear.  These are smaller, and don’t sting.  Much of the swarming actvity that is so obvious at the moment is courtship behaviour, and a very high proportion of the wasps, at least round N8N HQ, appear to be males – so those swarms may not be as big a health hazard as they seem.

Hold it a minute!

If you have a bunch of paper wasps at your place, have a closer look and see if you can tell how many females you’ve got, since there are really the only ones to worry about.  They stand out among the males as being bigger and blacker.  They have faces which are striped yellow and black, while males’ faces are almost entirely yellow; males also have antennae that are curled at the end, and more extensive yellow colouring overall.  If you’re struggling to see the differences, try spraying a few and checking them out more closely once they’re dead.  But be careful, because it’s possible to get a sting even from a dead female.

After mating the males die, while the females retire to sheltered spots such as woodpiles to over-winter. (Last winter I had to wear gloves when collecting wood from the shed, because of all the hibernating wasps, which can still sting.)

They gather fibre from wood and plants, which they mix with saliva to form small paper nests, usually up to about 10cm in diameter.  These mostly hang from vegetation or under eaves, but can also be in more confined spaces such as under roofing tiles.  Asian paper wasps are considered to be less aggressive than German wasps.   They were first recorded near Auckland in 1979 and by the early 2000s were established around here.

German wasp (Vespula germanica)

These are plumper than Asian wasps, with smooth bodies, 12 to 17mm long (although queens are larger.)  They have more yellow colouring than Asian paper wasps and have black dots on either side of the back.  They are aggressive, and will sting humans, animals and insects.  Their nests are also made from paper, but are much larger, and usually underground.  Queens appear in the autumn, obvous from their large size, and over-winter much like paper wasps.  Hibernating queens tuck their wings under their legs, so that at first sight they may appear wingless.  They have been in the country since the 1940s.

Common wasp (Vespula vulgaris)

Similar to the German, but have more extensive areas of black – the black dots along the back are partially or entirely incorporated into the stripes.  Their sting is also nasty. Common wasps became established in New Zealand in the 1970s and they are now the main wasp in beech forests.  Round here they became established in the 1980s, and seem to be displacing the German wasps.

Australian paper wasp (Polistes humilis)

These sensitive souls don’t like frosts and live in warmer, coastal areas so we don’t see them around these parts.  They’re slightly smaller than Asian paper wasps and orange-brown in colour.

Dealing to paper wasp nests

Although it is tempting to have a crack at them when you discover the nest, wait until evening or first thing in the morning when the wasps are, literally, chilled.

We – well, the husband – has destroyed at least 20 paper wasp nests this season and we’re still discovering them.  He notes where the nest is and then comes back later with the flyspray.  Once the wasps are gone remove the nest and burn it if possible, as other wasps will plunder it for material for their own building projects.

German wasp nests

These are a little trickier to deal with but they can be destroyed.  Once you notice the wasps try to follow their flight path to discover their nest. You can (carefully) flick white flour on the critters to make it easier to track them.

Visit the local hardware shop for a suitable insecticide – a friend recently had success using Carbaryl powder.  She  carefully puffed the poison through a tube down into the nest, taking great care not to inhale.

Keith Holborow also uses Carbaryl – he put the powder into a jar lid nailed on to a long stick and puts it into the nest with that.

“I just walk quietly around, and look and listen for them. They nest in the ground, and you can see them coming and going. Often there will be little white chips outside it, which is another give away. If the hole has spider webs or leaves in it, look elsewhere because it’s not active.”

Update: Carbaryl is now discontinued in New Zealand, ask your garden centre for advice on products.

What to do (or not to do) around wasps

Stay calm.  Keith advises staying out of their flight path if you possibly can.

“Everybody has their pet theory about what to do if wasps get angry, some people recommend running like crazy, but you should run with dignity, not slapping yourself. Every person I’ve ever seen stung by a wasp has swatted at them. While it’s an understandable reaction, it’s the worst thing to do. Move away steadily.”

Another option is to freeze. “This seems to work well too, as long as you have the self-control to watch a wasp hovering past your eyes, checking you out. You hope they won’t do anything more about it, and almost for sure they won’t.”

He had received differing advice from the experts – “The Auckland Park rangers say run, run like hell, but the Auckland Park wasp exterminator says freeze and stay out of the flight line. When they lose interest, walk away quietly. And that always seems to work for me.”

And if you are in the bush, he says carry antihistamine and a first aid kit with you.

Dang, I’m stung – now what?

Usually wasp stings cause only local reactions but sometimes severe allergic reaction occurs – ring 111 if needed.

• If stung on the neck, face or in the mouth, take an antihistamine and see a doctor immediately.  Stings can cause swelling in the throat, making it difficult to breathe.
• Otherwise, apply an ice pack on the area,  or apply antihistamine cream (and take it easy for the rest of the day.)

So, wasps are out and about their business.  At least we can take comfort from the fact we don’t have Japanese giant hornets.

 

Thanks to David Riddell for help in compiling this article.  Click here for Waikato Regional Councils guide to wasps. For advice on control methods, call Waikato Regional Council’s animal pest control on 0800 246 732.

• For an alarming yet entertaining story on exactly how evil wasps are, click here.

Postscript:

Recently at Waikorea Beach, between Raglan and Waikato Heads, we found another species of wasp washed up dead along the high-tide line. After a bit of research we learned it was a female yellow flower wasp (Radumeris tasmaniensis). These Australian wasps were first seen in this country only in October 1999, near Cape Reinga, and have since been found as far south as the Bay of Plenty. They lay their eggs on the larvae of large scarab beetles, which in New Zealand seems to be mainly the sand scarab, found in sand dunes, so their distribution is mostly coastal. Because they may pose a threat to native scarab beetles they are regarded as Unwanted Organisms in New Zealand, but they are otherwise largely harmless, feeding as adults on flowers, and not known to sting people.

Yellow flower wasps are large (up to 3cm long, males are smaller), with black and orange stripes on the back, and none of the black dots that common and German wasps have. The undersides are mostly black with narrow white stripes. They have a characteristic flight pattern, flying in horizontal figure-eights, up to a metre above the ground.

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