Britain’s wasps have gone missing after ground temperatures passed 50 degrees

Britain usually spends late summer fending off wasps at picnics and calling exterminators for backyard nests. This year, the wasps simply did not show up in the usual numbers, and the scientist who studies them says an unusual mix of temperature extremes may be the reason a normally resilient insect appears to be struggling.

A Quiet Summer That Worries a Wasp Biologist

Seirian Sumner, a professor of behavioural ecology at University College London, says common social wasps have become strangely scarce across the United Kingdom during the summer of 2026, to the point that her own students have struggled to find wasps for their research experiments. She points to a second sign that something unusual is happening: the near-total absence of the “plague of wasps” news stories that typically accompany a warm summer. Professional pest controllers have told her it has been an unusually quiet year for nest-removal calls. Sumner is careful to note these are anecdotal observations rather than confirmed data, since the UK’s only national wasp-monitoring effort, the Big Wasp Survey, had not yet begun its 2026 sampling season at the time of her report.

A Decade-Old Survey Built on Beer Traps

Sumner co-founded the Big Wasp Survey in 2017 with Adam Hart, a professor at the University of Gloucestershire, specifically to counter widespread negative attitudes toward wasps while building a genuine picture of their diversity and distribution across the country. The method has stayed simple since that first season: volunteers build a trap from an old plastic bottle baited with a splash of beer, hang it in a garden for about a week, and either send in the catch or, since the COVID-19 pandemic pushed the project toward remote participation, learn to identify their own wasps using instructional videos. The approach has already proven itself scientifically. A 2023 genetic study built on Big Wasp Survey samples found a single, well-mixed population of the common wasp spanning the whole of Britain, distinct from a more genetically separated population across the Irish Sea in Northern Ireland, and the resulting distribution maps held up well against four decades of expert-collected records. The 2026 season marks the survey’s tenth year, giving Sumner’s anecdotal observations of a scarce summer an unusually deep baseline of prior data to eventually be checked against, once this year’s samples are collected and identified.

A Strange Spring Set the Stage

The trouble, according to Sumner, may trace back to an unusual spring. Warm, dry conditions early in the season initially favored wasp queens emerging from hibernation to found new colonies alone, a high-risk period during which a single queen must handle nest building, egg laying, foraging, and brood rearing without help. Normally, warm and dry spring weather improves a young colony’s odds by ensuring good nectar supplies and healthy prey populations. But 2026’s spring brought unprecedented heat for the season punctuated by cold, damp days and unexpectedly chilly nights. That volatility may have driven queens to abandon their nests or die outright, shrinking what would typically be a healthy founding population before the colonies ever had a chance to establish themselves.

Ground Temperatures That Outran a Wasp’s Limits

Then came the heatwaves, which arrived one after another through the summer. Every insect has what scientists call a critical thermal maximum, or CTmax, the point beyond which desiccation, muscle spasms, and eventual collapse set in. For honeybees, that threshold sits around 49 degrees Celsius, yet ground surfaces during this summer’s UK heatwaves exceeded 50 degrees Celsius. Common wasps appear to have an even lower estimated ceiling, roughly 45 degrees Celsius, which may have left them especially exposed to the extreme ground-level heat recorded this year. Wasps are generally considered one of the more heat-resilient social insects thanks to behaviors like wing-fanning to cool larvae, insulating nest architecture, and waxy cuticular hydrocarbons that shift structure under heat stress to reduce water loss. Even those defenses, Sumner suggests, may not have been enough against ground temperatures this extreme.

Why the Survivors Look Smaller Than Usual

Sumner also noticed something odd about the wasps that have appeared: many are unusually small. Wasp body size is fixed during larval development and depends heavily on how much food a larva receives before pupating. Early-spring workers are typically small because a lone queen can only provide so much food, while workers emerging later, once a colony’s foraging capacity has grown, are usually substantially larger. This year, Sumner reports still seeing “spring-sized” wasps well into what should have been the colonies’ bigger, better-fed phase. She suggests two possible explanations: limited prey diversity and abundance may be restricting larval nutrition, or the heat itself may be accelerating development, causing larvae reared at higher temperatures to pupate faster and at a smaller size. Research has already linked long-term global warming to a documented shrinking trend in social wasps over the past century, and Sumner suggests this summer may be a real-time glimpse of that pattern accelerating.

Why a Missing Wasp Population Matters

A thinner wasp population is not simply a footnote for anyone who dislikes them at a picnic. Wasps serve as pest controllers, pollinators, and decomposers within UK ecosystems, and Sumner argues their apparent decline this year deserves attention precisely because they are usually considered tough and adaptable, unlike more heat-sensitive pollinators such as bumblebees, which conservation groups have already flagged as vulnerable to this year’s extreme weather. Confirming whether 2026 represents a genuine population crash or a temporary anomaly will depend on data from the Big Wasp Survey once its sampling gets underway, along with citizen-collected observations researchers are gathering through public surveys this season. Until then, the missing wasps stand as an early, unconfirmed signal of how extreme heat could reshape even the hardiest insect populations across Britain.

This article was created with the assistance of AI and reviewed by an editor.

More from Morning Overview