Multiple mating means the queen dilutes the relatedness of the workers in her brood and workers end up rearing a mix of half- and full-siblings, which can break the social contract of the colony. In these cases, workers can do better, individually, if they lay their own eggs. And this is when things get messy: sneaky egg laying by workers can cause a colony’s cohesion to break down, creating internal battles among the workers. They may be bloodless battles, as no insect blood (haemolymph) is shed, but they’re fought by ruthless means: workers that detect another worker’s eggs will eat them before they hatch.

But aren’t we taught in schools that only queens lay eggs? In fact, workers in almost all Hymenoptera (bee, wasp and ant) colonies can lay eggs. Because of a genetic quirk of the Hymenoptera, females hatch from fertilised eggs and males from unfertilised eggs. Worker wasps have lost the ability to mate, but can still lay male (unfertilised) eggs. 

How can wasps help humans?

There are other reasons to admire wasps. For one thing, they may be indirectly responsible for the invention of paper. Around 2,000 years ago a Chinese eunuch called Cai Lun noticed a wasp building a paper nest in his garden. Inspired by what he saw, he started to mulch wood and with it made the first paper. If the story is true, then perhaps we have wasps to thank for much of our rich cultural history and development.

Fast forward to today where exciting research is looking into the potential use of wasp venom as a cancer therapy. An active peptide found in the venom of tropical social wasps selectively destroys cancerous cells by causing their membranes to leak. Wasps may have the potential to save human lives.

A better appreciation of the ecological, economic, medical and cultural services that our stripy friends provide might help us see them in a different light. So next time your picnic is disturbed by black and yellow insects, take a moment to think about their extraordinary world and the contributions they make to our lives before you reach for the swatter. 

More related content:

• Guide to UK insects that bite or sting: how to identify and avoid being bitten
• UK sand dune guide: best dunes to visit and wildlife to identify
• Garden pond guide: how to look after your pond and wildlife to spot

---

The lifecycle of social wasps

1

The queen wasp emerges from hibernation

A single-mated queen emerges from winter hibernation in the early spring. Her workers build a nest in a cavity in the ground or a tree, and only after the nest is fully established will she build each cell and lay an egg in it.

2

Her offspring emerge

After about 30 days, her first offspring – the workers – emerge as adults. They’re all female at this point. The workers takeover the foraging, brood care and nest building and maintenance duties; the queen becomes a stay-at-home egg-laying machine.

3

Larvae hatch

After a few days carnivorous larvae will hatch from the newest eggs. The adult workers bring insects back to the nest to feed to the hungry larvae, which offer a sugary reward to the workers, via a process called trophallaxis. The larvae grow over a couple 
of weeks before they spin their pupal cap and pupate.

4

The colony grows

Over the next couple of months, the colony will grow, possibly to include thousands of wasps, depending on the species. Once the colony is big enough, the queen will switch to laying a sexual brood: these are males and the sexual females capable of becoming next year’s queens.

5

Wasps mature and leave the nest

When the sexual brood emerges, they leave the nest to mate and then find somewhere to hibernate over the winter (lofts are a popular choice). After this point, the nest has served its purpose but the workers are still alive with no brood to feed – this is when they start to bother you.

---

How many wasp species are found in the UK?

In the UK there are approximately 9,000 species of wasp. This includes larger wasps species that sting and microscopic parasitic wasps that can’t be seen with the naked eye. Here are some of the most common wasp species found in Britain.

Common/German wasp (Vespula vulgaris/germanica)

These are the wasps most likely to upset your picnic. V. germanica tends to be more bad tempered than V. vulgaris. These two species are practically identical but you can tell them apart by their facial and thorax markings. Both species have a single queen who produces 6,000 to 10,000 workers. They make football-sized nests in the ground or in roofs and trees.

European hornet (Vespa crabro)

The European hornet is about twice the size of the other social wasps but despite its looks is unlikely to bother you at picnics. Hornet colonies have a single queen and around 100 workers. They like to nest in tree cavities or bird boxes.

Yellow-legged Asian hornet (Vespa velutina)

This Asian species is a voracious predator of honeybees that was inadvertently introduced to southern Europe in 2004. It’s now widespread in France, Spain, Italy and Belgium, but not the UK, which has an effective extermination protocol for dealing with these invaders. Suspected sightings can be reported using the Asian Hornet Watch app (available for Apple and Android devices) or by emailing details and photos to the Centre for Ecology & Hydrology alertnonnative@ceh.ac.uk.

Red wasp (Vespula rufa)

Red wasps have a distinguishing red tinge on their abdomens. Their nests are smaller and always underground. A single queen will produce around 300 workers. The colony cycle of V. rufa is shorter than V. vulgaris/germanica, ending in late August.

Dolichovespula species

There are three species of Dolichovespula in the UK. The most common is Dolichovespula media. You can tell them from Vespula as they’re bigger and have blacker abdomens and are only seen in early-mid summer. Their new queens leave the nest in early August and thereafter the colony soon winds down.

---

Why do wasps sting in autumn?

Wasps tend to be at their most irritating in October – but why? The answer actually lies in the unusual ecology and bizarre anatomy of social wasps. In the spring, queen wasps wake from hibernation and start to build their nest, laying eggs and raising their first brood of daughters. These worker wasps cannot produce fertilised eggs so spend their time helping their mother expand the nest and raise more young.

One of their main jobs is searching for soft bodied invertebrates to feed the developing larvae. Bizarrely, adult wasps cannot digest the food they catch because their gut is so constricted by their thin “wasp waists”. Instead the workers chew up the prey and feed it to the larvae. In return the larvae produce a sugar rich spit that the workers can drink.

Social wasps only really become a nuisance in late summer. At this time there are no larvae left to feed so instead of hunting for prey the workers turn their attention to sugar (nectar and your picnic). Wasps sting to defend themselves – this is an evolved strategy to combat vertebrate predators at the nest: swatting at them may elicit the same innate collective behaviour. Some wasps’ stings trigger the release of an alarm pheromone that attracts more wasps. To minimise the nuisance, try to isolate the first wasp to appear under a glass but don’t forget to release her at the end of your picnic.

---

Could wasps provide an alternative to meat?

Wasp larvae are a sustainable alternative to meat. Over 2 billion people in 80% of the world’s countries feast on insect protein every day. Wasps represent about 4% of the insect species consumed and are the most common edible insects on sale in rural China. In fact, a new cottage industry of wasp harvesting in ‘Vesparies’ is springing up in Japan.

---

The author

 

Dr Seirian Sumner is a behavioural ecologist at University College London. Her research focuses on understanding how and why animals and insects such as wasps live in societies.

---