Britain could face a surge in flies and other pest insects this summer after wasps appear to have largely disappeared across the country, a scientist has warned.
Seirian Sumner, a professor of Behavioural Ecology at University College London, said there have been an unusually low number of wasp sightings in the UK so far this summer. She said the most likely cause is the exceptionally hot and dry spring, which created difficult conditions for queens trying to establish new colonies.
Without healthy wasp colonies, populations of flies, aphids, caterpillars and other insects that wasps normally hunt could rise sharply later in the season.
“Their absence greatly worries me,” Professor Sumner wrote in The Conversation. “Love them or hate them, wasps are important in ecosystems as pest-controllers, pollinators and decomposers.”
Each spring, a single wasp queen emerges from hibernation and must build a nest alone before raising the first generation of workers. If she dies during this vulnerable period, the entire colony is lost. Professor Sumner said this year’s weather extremes, which combined unprecedented heat with cold, damp days and chilly nights, may have caused queens to abandon their nests or die.
She noted the contrast with last year, saying that the same period in 2025 saw media coverage full of “plagues of wasps” stories. This year, she said, even professional pest controllers are reporting a quiet season with very few requests to remove nests.
A healthy wasp colony can contain several thousand workers by August, each hunting insects to feed the growing brood. Fewer colonies means less predation, giving pests such as flies a greater chance to thrive.
Professor Sumner said it is too early to know whether wasp numbers will recover later in the season. She urged people who encounter wasps this summer not to shoo them away, noting they may be searching for protein or sugar to sustain themselves and their brood.
There are roughly 9,000 species of wasp in the UK, though only a handful regularly sting people or become a nuisance around food. The common wasp and German wasp are the two species most often seen in British gardens during late summer.
