Another Life: A defence of the much maligned wasp

The wooden door of our old greenhouse, scoured by rain and wind, has weathered to a shade of silvery-grey that Farrow and Ball decorating paints might attempt.

The queen wasp I found busy at its surface was seeking her own use for its fibres – not as trendy wall-paint but for chewing up in pulp to make the cells for this year’s nest. The strips she tore off left pale scars on the door.

Where the nest might be I’ve no idea; quite probably underground. But it’s a new one every year, started by a queen wasp out of hibernation and initially the size of a golf ball. It grows rapidly in size as the numbers of wasps increase – hence the abandoned paper footballs surviving in odd corners of outside sheds or roof-spaces. We’ve plenty of either but have never found a nest.

Nor, for that matter, have we ever been stung by a wasp. That makes it easier to join the growing chorus of approval and recognition for the role of the aculeata – wasps equipped with a sting – in the balance of insects and plant life. Without them, as without bees or moths, the health of the planet’s vegetation would suffer even more.

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In late summer the release of working wasps from feeding duties sends them off seeking sugar. Some prospect for sweetness at beer gardens, kitchen tables and wine glasses. For the trivial mayhem that may then occur, wasps as a whole have been maligned and their proper respect diminished.

To help put this right is a crusade for Dr Seirian Sumner, a reader in behavioural ecology at the University of London. As part of it, with Prof Adam Hart, Sumner set up the Big Wasp Survey, a citizen science project to sample populations of social wasps across the UK.

‘Alternative to meat’

Thousands have hung up wasp traps in their gardens (old plastic bottles with a little beer in the bottom) and returned the dead insects for identification. A recent summer yielded some 18,000 wasps, useful for data but also recruiting interest in what many have always seen as pointless pests.

Dr Sumner's latest paper, in Biological Reviews, is the first comprehensive review of the wasps' ecosystem services as pollinators and pest controllers, decomposers and seed dispersers. She and her team also find their larvae "a sustainable alternative to meat for human consumption" .

It’s a global view, focused on the kinds of wasps with a sting, most of which lead solitary lives. Many are insect hunters, bringing prey back to small nests in holes in the ground. Others are parasites, such as tiny wasps that plant eggs in caterpillars as nurseries and food for their young.

The larger, more familiar “social” wasps, of which there are half-dozen species in Ireland, form only 3 per cent of the world’s wasps with stings. With many thousands per nest, however, their impact as insect predators is huge: perhaps even greater, says Dr Sumner, than the year-round consumption by insect-eating birds.

A nest of the common wasp, for example, will produce some 9,600 adults in its cycle, including more than 7,000 workers and almost 900 queens. One nest can consume half a kilo of prey as protein food for its young. This harvests and controls a huge variety of arthropods; everything from flies and caterpillars to ants, grasshoppers and spiders.

Short tongues

Solitary wasps tend to have specialist tastes in prey, or for parasitism, giving them potential as a biocontrol of pests. Social wasps are opportunistic, random hunters, but Dr Sumner sees a similar potential for them, especially in tropical crops, in “artificially inflated populations”.

Social wasps have short tongues for seeking nectar, which explains their springtime throng on the massed, shallow flowers of our big cotoneaster. The new study found 164 plant species that depend solely on wasp pollinators, with some orchids showing specific co-evolution with the insects.

Lack of research has long hidden the pollinating value of stinging wasps compared with bees. But the potential of their larvae as “a viable, healthy alternative to eating meat” is another of Dr Sumner’s enthusiasms.Two billion people across the globe, she points out, already eat more than 2,000 insect species.

Wasp larvae, farmed for food, have an exceptionally dry protein mass, typically contain some 70 per cent of required amino acids, and are extremely low in fat. They currently account for less than 5 per cent of human insect food, but Dr Sumner’s team found reports of their consumption across 19 countries. During the autumn harvest in Japan, “wasp nests typically sell for $100 per kilo”. The grubs are also “a popular street food” in east Asia, Africa and South America.

Insect farming, as she points out, takes up less space and water than meat production, has a much higher food-conversion and emits fewer greenhouse gases – wasps, one assumes, don’t belch methane.