Wasps. The very word might evoke images of painful stings and disrupted picnics. Often seen as aggressive pests, wasps have unfortunately earned a negative reputation. However, beneath this perception lies a fascinating truth: wasps are not villains, but vital players in our ecosystems. These incredibly diverse insects perform a multitude of essential tasks that are crucial for a healthy environment.
While many people are most familiar with the black and yellow social wasps that can become unwelcome guests at outdoor gatherings, the world of wasps is astonishingly varied. In the UK alone, over 7,000 species exist, encompassing both social and solitary varieties. A significant portion of these are parasitoid wasps, whose young feed by consuming other insects or spiders, often while they are still alive. Despite the less endearing habits of some, and our common frustrations with their stings, ecosystems worldwide depend on these often-overlooked insects.
So, beyond simply being a nuisance, what exactly is the purpose of wasps? Let’s delve into the beneficial roles they play in the natural world.
Wasps: Nature’s Pest Control Experts
Perhaps wasps are most notorious for their unwelcome appearances at summer meals, but their role as natural pest controllers is undeniably significant. They are, in fact, invaluable allies in maintaining ecological balance and providing us with a form of natural pest management.
Imagine a world overrun by insects and spiders. It’s a scenario that could become reality without the diligent predation of wasps. Each summer in the UK, social wasps are estimated to capture an astounding 14 million kilograms of insect prey, including caterpillars and greenfly, both of which are common garden pests. Far from being mere pests themselves, wasps are actually a gardener’s best friend, working tirelessly to keep populations of other insects in check.
Common wasps feeding on a piece of browning pear
According to wasp expert Dr. Gavin Broad, “Wasps are generally apex predators – so if they’re not doing well, it indicates that there is something wrong with the world.” This statement underscores their importance as indicators of a healthy ecosystem. Their presence and activity reflect the overall well-being of the environment.
However, the very appetite that makes them beneficial in their native habitats can become problematic when wasp species are introduced to new environments without natural controls. A stark example of this is seen in New Zealand, where common and German wasps were accidentally introduced. In the absence of natural predators and competitors, these wasps have thrived, devastating local caterpillar populations in forests. This, in turn, has had cascading negative effects on the ecosystem, contributing to the decline of native bird populations that rely on caterpillars as a food source.
The Wasp Diet: Sugar for Adults, Protein for Larvae
It’s a common misconception that wasps eat the insects they hunt. In reality, adult wasps have a sweet tooth! They primarily feed on sugars, obtaining these carbohydrates from sources like flower nectar and honeydew, a sugary substance produced by aphids. However, the insects and spiders they capture are destined for their young, the wasp larvae.
Social wasps are meticulous hunters. They capture insects, meticulously chop them into smaller pieces, and transport these protein-rich portions back to their nests to feed their developing larvae.
Solitary wasps often exhibit even more specialized and sometimes gruesome hunting behaviors. Spider wasps, for example, including the formidable tarantula hawk, are masters of paralyzing their arachnid prey with a venomous sting. Once immobilized, the spider becomes a living food source for the wasp larva, which will devour it alive. Globally, there are nearly 5,000 species of spider wasps, with 44 of these found in Britain, showcasing the diversity within this group.
Another fascinating example of solitary wasp specialization is the velvet ant. Despite their name, velvet ants are actually wasps. Female velvet ants are parasitoids, laying their eggs on the pupae of other insect species. When the velvet ant eggs hatch, the larvae consume the defenseless host pupae, ensuring a meal for their development.
A common wasp gripping onto a small fly with its mandibles
Adult wasps, both social and solitary, rely on sugar for their energy needs. Besides nectar and honeydew, they are also attracted to sugary substances found in human environments, which explains their presence at picnics and pubs. As Dr. Broad explains, “There is also a lot of sugar at pubs and picnics. Adult wasps don’t live very long, so they don’t really need protein. They’ve just got to load up on carbs.” Their adult lifespan is relatively short, and their focus is on fueling their activities with readily available carbohydrates.
Accidental Pollinators: Wasps Contributing to Plant Reproduction
While bees are widely recognized as the primary pollinators, wasps also play a role, albeit often underestimated, in plant pollination. As wasps forage for nectar, they inadvertently transfer pollen from flower to flower, acting as accidental pollinators. Although their pollination efficiency may not match that of bees, wasps still contribute to the crucial process of plant reproduction, further highlighting their ecological value.
A black and yellow wasp on a large white and yellow flower
Seasonal Lives: Wasp Hibernation and Colony Cycles
The life cycle of wasps in temperate regions like the UK is strongly influenced by the seasons. Their activity is concentrated in the warmer months when insect prey is abundant, providing ample food for their developing young.
As autumn approaches and temperatures drop, the worker wasps of social species typically die off. However, newly emerged female wasps, destined to become queens, enter hibernation to survive the winter. They seek out sheltered locations such as attics and animal burrows to spend the cold months in a dormant state.
Only a fraction of these hibernating queens will survive the winter. Those that do emerge in the spring as the weather warms up, ready to initiate new colonies. A queen wasp begins by constructing a small nest and then lays eggs, which will hatch into the first generation of worker wasps. These workers then take over nest building and foraging duties, allowing the queen to focus on egg-laying and colony expansion.
Common wasps on a paper nest
Dr. Broad explains the colony growth process: “At the beginning of April and May the colony is really small, with just a few workers. Growth is slow until you get to a certain mass, then it’s almost exponential growth.” As the worker population grows, the colony’s foraging capacity increases, leading to a rapid expansion in size and activity throughout the summer.
The evolutionary history of common UK wasps, whose ancestors nested in cavities, has pre-adapted them to thrive in human-modified environments. This is why they frequently build nests in sheds, attics, and other man-made structures, sometimes leading to conflicts with humans as colonies grow large.
However, in Britain and similar climates, wasp colonies are ultimately limited by the onset of winter, which curtails their growth. In warmer regions with milder winters, wasp colonies can reach truly enormous sizes. “I think the biggest common wasp nests are in Australia,” notes Gavin. “There can be as many as two million workers. When you get a huge nest, you can imagine the large biomass of insect prey they’re taking in.” These massive colonies exert a significant impact on their local insect populations.
A wasp nest in a bowler hat
Wasp Stings: Defense, Not Offense
The wasp sting, the source of much human-wasp conflict, is primarily a tool for defense and subduing prey. Wasps utilize their venomous sting to paralyze insects and spiders they hunt and to protect their nests from perceived threats. They will also sting in self-defense if they feel threatened.
Sometimes, wasps sting humans because they perceive us as a threat, even if we are not intentionally posing one. It’s important to understand that wasp stings are not acts of aggression in the human sense, but rather defensive reactions.
Unlike honeybees, wasps do not suffer fatal consequences from stinging. Honeybees have barbed stings that become lodged in the skin of mammals. When a honeybee attempts to withdraw its sting, the barbs cause it to detach from the bee’s abdomen, resulting in fatal injury. “Honeybees have weak attachments in their abdomen. So when it pulls away the sting remains attached to you and it basically pulls away the entire muscle system around the sting. It’s a bit brutal,” explains Gavin.
Wasps, in contrast, possess smooth stings that can be easily withdrawn from the skin of their target, allowing them to sting multiple times if necessary. They can also replenish their venom supply, ensuring they are always equipped for defense and hunting.
The stinger of a black and yellow wasp
Common Wasp Species in the UK
If you encounter a wasp in Britain, it is most likely to be either a common wasp (Vespula vulgaris) or a German wasp (Vespula germanica). These two species are very similar in appearance, sharing a predominantly yellow body with black markings and being of comparable size.
Gavin adds, “The red wasp, Vespula rufa, and the tree wasp, Dolichovespula sylvestris, are also common. The Saxon wasp, Dolichovespula saxonica, only arrived in Britain in the 1980s and it’s mainly common in the south.” These species also contribute to the diverse wasp fauna of the UK.
“The European hornet, Vespa crabro, is quite common in parts of the south, but it is more of a woodland species.” The European hornet is the UK’s only native hornet species and is the largest social wasp in Britain. It also exhibits yellow and dark patterning, similar to other social wasps. This shared coloration among various well-defended wasp species is an example of Müllerian mimicry, where species benefit from resembling each other’s warning signals.
While the European hornet’s sting is reputed to be more painful than that of other common social wasps in Britain, causing throbbing pain for a few hours, it is generally not considered dangerous unless an individual is allergic.
A common wasp specimen
Since 2016, the yellow-legged hornet (Vespa velutina), also known as the Asian hornet, has been sighted annually in the UK. This invasive species is a specialized predator of honeybees and poses a threat to bee populations.
Despite the summer annoyances and stings that lead some to question their value, wasps are undeniably crucial for maintaining a balanced and healthy ecosystem. A world without wasps would be a world facing significant ecological challenges. These fascinating insects are not just pests, but essential workers in the intricate web of nature.
