BWe think of them as pests that we have to run away from or squash with the nearest object before they sting us or target our jam sandwiches. But wasps are actually one of the most fascinating species of all: apex predators that kill and dismember their prey for their young and lead complex and fascinating social lives.

This year they are in the spotlight after experts found they are not present in the usual numbers. Unlike butterflies and bees, there is no nationwide effort to record the wasp population; they are greatly neglected in the public eye.

This is despite the fact that there are over 100,000 described species of wasp, 9,000 of which are in the UK, and scientists estimate that five to ten times that number are still undiscovered. Most do not sting, and the vast majority of wasp species that do sting are solitary, hunting only specific types of prey. The wasps and hornets that sting humans only make up around 70 species worldwide, and there are only nine of these in the UK.

Dr Seirian Sumner is an entomologist at University College London who has studied wasps throughout her career. She said she was “thrilled” that people were concerned about the low wasp population because “they only usually get mentioned in the news when they start bothering people”.

“The fact that the low wasp numbers are making people sit up and take notice and, if I may say so, worry about whether the lack of wasps is a bad thing is really heartwarming for someone like me who has been a cheerleader for wasps against a barrage of wasp scaremongering and negativity.”

However, she is not surprised by the low numbers this year: “Science tells us that cold, wet springs mean that foundresses – the large queen wasps that emerge in spring – have difficulty successfully building a nest. This is because at this time in the colony cycle they are solitary and so have to do the nest building, egg laying and prey hunting all by themselves. Rain and cold make this difficult; and of course their prey is also affected by the bad weather, which adds to the challenge. So, because there are fewer successfully founded nests in spring, there will be fewer adult nests now. And predictably, there will be fewer wasps bothering people.

“This is bad news. Wasps perform many important roles in the environment, they are natural pest controllers, pollinators and in the case of the yellow jacket, they are also important decomposers – which is why they are so happy to eat the carrion at your barbecue,” said Sumner.

In the long term, the wasp population is expected to decline overall due to human activities, she said. “Chemicals such as pesticides will affect them in the same way as other insects – after all, these chemicals are designed to affect the physiology and neurology of insects.”

The wasp species that have fascinated many scientists are usually parasitoid species. These fascinating creatures are little studied and include the smallest insect in the world, the fairy wasp Dicopomorpha echmepterygiswingless and blind and about 0.127 mm long. They are usually out of our field of vision and are useful because they control other insects such as caterpillars by feeding on them.

Social wasps are the ones we’re most likely to come into contact with, especially when they’re older and looking for sugar – hence the appeal of the jam sandwich; they build nests and divide into workers and queens, much like bees. Then there are solitary wasps, which have a laser-like focus on their specific prey, from honeybees to spiders. These wasps, like parasitoid wasps, are unlikely to come into contact with humans unless they accidentally stray and enter our homes. And all of them, along with ants and bees, belong to the Triassic insect order Hymenoptera, the “membrane-winged” insects.

At the Natural History Museum, Dr Gavin Broad is responsible for looking after the institute’s wasp collection and, as you might expect, he is quite fond of them: “Wasps are apex predators that keep pests at bay and are generally pretty tough. It’s impressive to watch a wasp fight with and dismember a large dragonfly. They go to great lengths to feed their young with fresh protein and it’s only the adult wasps, particularly at the end of the breeding season, that require sugar and that’s when they come into conflict with humans.”

Humans have learned a lot from wasps: “Watching social wasps build their paper nests gives you a sense of how humans may have originally come up with the idea of ​​making paper from wood pulp. These nests are architectural wonders; I enjoyed watching wasps painstakingly build their nests from strips of papier-mâché one after the other, and watching and listening to them chew wood to make their pulp.”

He added: “They are a wonderful group to study because there is still so much to learn about their ecology. Even in Britain you can find undescribed species. I am describing a new species of nocturnal parasitoid wasp that turned up in my garden light trap. The sheer efficiency of many parasitoid wasps is wonderful – and bloody. Very often a caterpillar turns out to be parasitized and you can watch the host disappear as it is completely consumed by wasp larvae.”

Prof. Charles Godfray teaches evolutionary biology at Oxford University and has been studying parasitic wasps for decades. “The larvae of parasitic wasps develop in the bodies of other insects and we think they are really important. To explain: if you look out the window and think about why the earth is so green even though there are so many things that eat leaves, it is because the caterpillars are controlled by parasitic wasps. They are extremely numerous and have a huge impact on the structure of ecosystems as we know them.”

The role of parasitic wasps in pest control is so important that scientists have bred and released them in areas where invasive pests had been accidentally introduced and threatened the food supply, Godfray says.

But wasps also exist for their own sake and deserve to be part of the ecosystem, he added, warning against looking at them only in terms of their benefit to humans: “I probably wouldn’t think about it in those terms – whether they are good or bad, they are simply part of our natural community.”

As an evolutionary biologist, he is interested in the evolution of social wasps – the kind that build nests and swarm around: “The really strange thing about wasps is that there are thousands of species, but only a small proportion of them have become social. They have developed a very strange social system where there is a queen and workers. Darwin spent a lot of time studying it; it was a great mystery to him. From an evolutionary point of view, wasps, along with ants and bees, are absolutely fascinating.”

While wasp enthusiasts used to only be found in the field or browsing libraries, social media has helped connect them, Godfray said. “There are simply too few people interested in these insects. Interestingly, there are now at least two Facebook groups of people interested in parasitic wasps, sharing photos and discussing identification questions. One of the positive things about the internet is that there are now so many resources. Now very dedicated citizen scientists can make important contributions.”