The Vulgar Wasp: How wasps became ingenious predators

by Jenny Nicholls / 16 April, 2018
German wasp

A macro image of a German wasp, with its two sets of eyes: three simple eyes, and two compound eyes. Photo/Getty.

Professor Phil Lester looks at the many sides of wasps and the challenges in pest control in his new book, The Vulgar Wasp.

Although Wellington professor of ecology and entomology Phil Lester has led many investigations into wasps, there is one he isn’t game to try.

Where does it hurt most to be stung? US entomologist Michael Smith can answer this question, in some detail. Over 38 days, he endured 75 bee stings to 25 locations on his body, from the top of his skull to the arch of his foot. Each spot was stung three times, for the sake of accuracy, and the pain rated on a scale of 1-10. The “best” places to be stung, says Smith, are the skull, the tip of the middle toe, and the upper arm, all rating 2.3.

Worst was the nostril, which he scored an eye-watering 9, followed by the upper lip, 8.7, and the shaft of the penis, 7.3. The scrotum, palm, cheek and armpit came next in the agony ratings, all scoring 7.

Smith noted that although every sting hurt, a sting to the nostril “was a whole-body experience”. If you had to choose between a sting to the nose or a sting to the penis, he told Lester, “you’re going to want more stings to the penis”.

Although Professor Lester was compiling a book about wasps (The Vulgar Wasp, Victoria University Press, $30), and not honeybees, he writes, “I imagine the results are similar and personally, I am not willing to repeat his experiments with wasps just to check.”

Lester’s fascinating book, which sifts decades of research for the everyday New Zealand reader, was published in early April at the peak of social wasp nest activity. In nests not far from you, new wasps were being made, a process Lester describes.

If the nest is grey, it belongs to a German wasp (Vespula germanica) colony. If the nest is pale brown or yellowish, it’s home to the common or vulgar wasp (Vespula vulgaris), one of the world’s worst invasive species.

Both are recent arrivals. All it really needed was a single queen, hibernating in a box of aircraft parts, say, or a piano – shipped, probably, from Europe. German wasps became established in the late 1940s; common wasps in the mid-70s.

Although “vulgaris” might sound like an academic insult, it’s simply the Latin word for “common” – a fitting name for a creature with such extraordinary powers of adaption.

There are many types of wasp: some social, like the Vespula; some solitary, too many to count; and some yet unknown. When the biologist J.B.S. Haldane was asked what one could conclude about the nature of the Creator from a study of his creations, he apparently replied, “An inordinate fondness for beetles.”

The beetle’s status as the order with the most species was challenged in March by US researchers from Cold Spring Harbour Laboratory. They pointed out that many parasitic wasps evolved to feed on particular beetles, so there could be “few scenarios in which there would be more beetle species than parasitic wasp species”. The order is vast and “relatively poorly understood”, they say, so no one knows how many there are. 

The argument that God is inordinately fond of parasitic wasps is never going to (ahem) fly. These wasps are plain creepy, laying their eggs on hosts, such as caterpillars, which become living larders for wasp larvae. The hosts’ fate, one of the worst we can imagine, inspired the film Aliens – and conniptions among those who seek moral meaning in nature.

“I own that I cannot see as plainly as others do, and as I should wish to do, evidence of design and beneficence on all sides of us,” wrote Darwin. “I cannot persuade myself that a beneficent and omnipotent God would have designedly created the Ichneumonidae [parasitic wasps] with the express intention of their feeding within the living bodies of caterpillars... A dog might as well speculate on the mind of Newton. Let each man hope and believe what he can.”

wasp

Wasps cost our economy at least $133 million annually – with more than half of that borne by the beekeeping industry.

Most people hate wasps. There is a photograph, in Lester’s book, of Chinese soldiers using a flamethrower to destroy a nest of Asian giant hornets, a species otherwise known as the yak-killer – the largest hornet in the world. “For some,” writes Lester in the caption, this approach is a dream method of dealing with social wasps.”

Although the yak-killer has, thus far, not booked a ticket to New Zealand, we have our own waspy world record. Our bush hums with the highest densities of wasps ever recorded. Anywhere.

The invading common and German wasp have found a land ripe for exploitation: a land in which their prey has not had time to evolve a means of escape, a land with winters so mild their nests sometimes survive and grow to gigantic size. A land of milk and honeydew.

In our beech forests, wasps have found a culinary bonanza, exuded by an estimated 20 million scale insects per hectare of beech forest. These insects eat tree sap and poo honeydew, rocket fuel for tūī, bellbirds, kākā and silvereyes.

And wasps. Researchers once counted 370 wasps per square metre of bark, foraging for honeydew. “Birdsong is absent from these forests in autumn,” writes Lester, “it’s replaced by the drone of wasps.”

There is thought to be a greater biomass of wasps in New Zealand honeydew beech forests than resident native birds, stoats and rodents combined.

In some forested areas, wasp densities have been measured at more than 40 nests per hectare. Researchers who placed native kōwhai moth caterpillars in a beech forest discovered their chance of surviving for three hours was 17%, and only 0.1% for a 12-hour day. “Clearly,” writes Lester, “there are unlikely to be many kōwhai moths in the beech forests of New Zealand.”

Many of the species that have been driven into extinction by these wasps will never be known, he says, because they’ve never been studied.

He calls wasps “a ferocious feeding force”. They eat nearly everything – spiders, stick insects, flies, weta, moths, grasshoppers, honeybees, honey and cicadas. They’ve even been known to gnaw on the teats of dairy cows.

The prey eaten by wasps is close in weight and composition to the entire intake of the insectivorous birds once common in these areas: cherished birds like kākā, small rifleman, fantails, warblers, whiteheads and yellowheads.

Wasps cost our economy at least $133 million annually – with more than half of that borne by the beekeeping industry. And there are other, more insidious environmental effects. Bees killed by wasps, or bees that stay at home nervously guarding their honey against wasps, are diverted from pollinating crops such as clover. To compensate, farmers use more fertiliser – which pollutes waterways.

Wasps are a formidable foe, and Lester cannot help but admire them. “They are a fascinating and ingenious predator, but also a ruthless invader – a pest – that we have a duty to manage,” he writes, almost reluctantly.

Research into solutions such as gene silencing and gene drives, he thinks, are our best hope of bringing the birdsong back to our humming autumnal beech forests. 

The launch of the book The Vulgar Wasp and a public lecture by Professor Phil Lester will be held at Victoria University, 5.30-7.30pm, Wednesday 18 April. Click here for more details and to register.

Waspish facts

Are there native wasps in NZ?
• Yes, but they’re not considered pests, like the social wasp invaders.
• There are no native social wasps.

What’s the difference between a solitary wasp and a social wasp?
• Social wasps construct large nests with a sophisticated social system.
• Solitary wasps either don’t make nests or make them only for their own offspring.

What’s the difference between a German wasp’s nest and a common wasp’s nest?
• German wasp nests are grey, whereas common wasp nests are brown.
• Both species often, but not always, build their nests underground.

When are social wasps active?
• Queens emerge from hibernation in spring (August to December) to make a nest. In summer (January to May), wasps are foraging and the nest expanding. In winter (June to August), the new queens hibernate and the nest usually dies.

Can wasps kill me?
• Yes. In 2012, a 62-year-old man suffered a heart attack in Kenepuru Sound after disturbing a huge wasp nest.
• It’s estimated that common or German wasps kill two people each year in New Zealand, from cardiac arrest or anaphylactic shock.
• From 2000 to 2013, stings from ants, bees and wasps killed more Australians than sharks and crocodiles combined.

I have a serious wasp problem on my property. How can I get rid of them safely?
• A Nelson-based company has developed with DOC a bait called Vespex. Wasps take it back to their nest, where it is shared among workers and, crucially, the queen, killing the nest.
• See doc.govt.nz/nature/pests-and-threats/animal-pests/wasps/

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