How has a tiny, flying insect become one of the most serious threats to New Zealand’s environment?

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Especially when we have all these other pests we keep hearing about like possums, rats and stoats.

To help understand the impact of wasps, we’d like to introduce you to Carrie the common wasp … and her European cousin, Gunter the German wasp.

Gunter arrived in New Zealand with aeroplane parts shipped from Britain after World War II. Carrie turned up uninvited in the 1970s.

The absence of natural predators, abundance of food and the mild climate allowed Gunter and Carrie to rapidly reproduce and spread across the country.

To give you an idea of how many vespula wasps there are, a nest can produce about a thousand queens, plus thousands of workers. There are up to 40 nests per hectare of beech forest. And there are more than one million hectares of beech forest in the South Island. That’s an estimated

(ten zeros) queens.

At its peak, the biomass of wasps in South Island beech forest is as great as, or greater than, the combined biomasses of birds, rodents and stoats

Gunter and Carrie have a varied diet, but they particularly like honeydew, an important food source for native birds, lizards, insects and honey bees. Wasps exploit at least half of all honeydew in upper South Island beech forests.

But not only do Gunter and Carrie eat a major food source of the forest. They also attack, kill and eat insects and newly-hatched native birds. They consume up to 8.1 kilograms of insects per hectare, per season - similar to the amount consumed by insect-eating birds.

All of this has wreaked havoc on New Zealand’s environment, causing drastic declines in native biodiversity.

Wasps also cost the economy more than $130 million a year, impacting on beekeeping, forestry, agriculture and tourism.

But there’s a social cost, too. Wasps sting people, ruin family picnics, mountain biking and walks in the bush. Occasionally, they even kill people.

And the descendants of Gunter and Carrie continue to spread. Experts are predicting an “explosion” in wasp populations this summer.

This means more damage to our environment, more risk to people enjoying the outdoors, and more need to significantly reduce wasp populations.

Words: Jonathan Carson
Animation: John Harford