When Christina Letanka moved to Chiddingly village in East Sussex 28 years ago, insects were everywhere. “Everything was prolific when we first arrived,” she says. The kitchen used to be full of flies during the day and moths at night, swarming under the light. “Now they’ve all gone.” Fewer butterflies, wasps and hornets dance around in the garden. “Normally everything comes out with the buddleia, but this year has been surprisingly bad – it’s dead,” Letanka says. “Is it the wet? I don’t know what’s happened. It’s been truly shocking.” Many concerned gardeners and nature lovers in Britain have noticed fewer insects around this year. Kevin Coward has been gardening in south Manchester for more than 40 years, growing a mixture of flowers, as well as fruit and vegetables. He used to love watching butterflies over a cup of tea. “I’ve had a huge reduction in butterflies, with no caterpillars until this past week,” says Coward. “I have not actually seen any larger moths this year.” He says it is “a problem noticed by other people in my village too”. The rumblings have reached social media, with gardeners voicing their alarm and posting photos of quiet, insect-free gardens. The former Top Gear host – and now farmer – Jeremy Clarkson also chimed in: “Just been for a walk round the farm and I’m a bit alarmed by how few butterflies there are. Something is afoot.” Does the data back up the anecdotes? Annual data on insect populations is limited, but the indicators we have say yes, it has been a bad year. “All year, stretching way back into the early spring, people have been contacting us (and indeed I’ve seen myself) that there seem to be relatively few butterflies around,” says Dr Richard Fox, an ecologist and the head of science at the charity Butterfly Conservation. He helps to run the Big Butterfly Count, which is one of the biggest citizen science projects in the world, with more than 50,000 people taking part each year. British butterflies and moths are probably the best-studied insects in terms of long-term data. This means butterfly numbers are often used as a proxy for how other insects are doing. Provisional data from the 2024 count suggests butterflies have had their worst year on record after a wet spring and summer. In 2022, it recorded its third successive year of record lows. The year 2023 proved an unexpectedly good one, but it appears the downward trend is continuing again this year. What is causing the declines this year? The short-term culprit is bad weather. March and April, which are crucial months for insects were cool, wet and cloudy. It was the UK’s wettest spring since 1986. Butterflies, for example, need some warm and dry weather to be able to fly around and mate. “Overall, the weather conditions in the spring have made it much more difficult than normal for insects to fly, forage, nest and just generally go about their daily lives,” says Dr Richard Comont, who leads the national bumblebee monitoring scheme, BeeWalk. “The summer has been slightly better, but not by much – still unseasonably cool for most of June and July.” Insects are very weather-sensitive, so there is always a lot of variation from one year to the next. They are used to bad weather, and generally bounce back when things get better, but a lot of bad years can results in long-term downward trends. Many populations have probably not yet recovered from the heat and drought of 2022 when temperatures in the UK passed 40C for the first time. “This isn’t happening in isolation,” says Comont. “[This year] was the fourth poor spring in a row, so spring-flying species are getting gradually ground down … There have always been poor-weather years, but this one is coming at weakened insect populations already reeling from a series of other extreme weather events – it’s really punching them when they’re down.” Are bust years becoming more common? The climate crisis is changing the natural rhythm of the seasons, which insects are finely tuned to, and makes extreme events – such as “never-ending” rain – more likely. While one bad year is not an indication that things have changed long term, unusual weather conditions are increasing in frequency. “As well as the weather just generally getting warmer, the extreme weather events are becoming more common,” says Matt Hayes, an ecologist at the University of Cambridge. “If that happens then a given population of butterflies might do well one year and then suddenly completely the wrong conditions happen the next. So the fluctuation seems to be becoming more common.” Extreme events appear to have more impact than the gradual temperature increase. “Years getting a little warmer on average … is less likely to be a problem for most butterflies than the much more unpredictable storms, heatwaves, droughts etc,” says Fox. What long-term data do we have? There are no rigorous long-term monitoring schemes for most insects, but researchers can still get an idea of how they are faring over time from sightings. For example, anecdotal evidence from gardeners, experts and pest controllers suggests that wasps have faced a sharp decline this year, with colder, wetter weather to blame. There is no long-term data to back this up. UK government data on nearly 400 bee and hoverfly species suggest that 42% have become less widespread since 1980. Long-running studies show that 80% of butterfly species in the UK have declined since the 1970s. Half of butterfly species are now either threatened, or near threatened, with extinction. Butterflies are a drop in the ocean in terms of insect species – there are only about 60 species of butterfly in the UK, but more than 24,000 insect species. We know they are very sensitive to environmental changes. “They’re the canary in the coalmine, to use the rather tired phrase,” says Fox. “They’re the best bet we’ve got for understanding how the rest of our insects are faring.” Most data focuses on the past 50 years. “We’re only catching the tail end of what’s probably a much bigger decline,” says Fox. “Overall that picture is pretty gloomy.” Insect populations are notoriously hard to measure because their numbers go up and down so much from year to year. They can increase or decrease 100- or 1,000-fold from one generation to another. In that sense they’re very different from birds and mammals and it presents a challenge for scientists monitoring them. “When you’ve got that variation from year to year, and then spread over thousands of species, you can imagine that data is incredibly messy,” says Fox. Best estimates suggest insect abundance is declining by 1-2% a year. What is causing long-term declines? Insect populations are dealing with multiple drivers of decline. Historically the main driver has been habitat loss due to the expansion and industrialisation of agriculture. The loss of flower-rich grasslands, heathland and peat bogs have driven a substantial decline in species that depend on those habitats. The rate of habitat destruction in the UK has slowed because many of these precious habitats are now protected. However, the quality of these habitats is being negatively affected by pollution from pesticides, nitrogen and even light. The climate crisis is also becoming an increasingly significant factor. Is it all bad news? Some species such as ringlets and speckled wood butterflies used to be restricted to more southerly parts of the UK, but as the climate has warmed, they’ve been able to spread into new areas. Ringlets have increased in number by more than 100% since the 1970s. There have also been some successful reintroductions in the world of butterflies, such as for the large blue, which went extinct in 1979, but was reintroduced using caterpillars from Sweden. In 2022, it enjoyed its best summer for 150 years in Britain thanks to targeted restoration work. “We’ve made a difference and stopped species from going extinct in Britain, so it’s not like it’s a completely hopeless situation,” says Fox. What can I do to help? Encouraging bee-friendly wild flowers, letting the grass grow long and avoiding pesticides will all help insects. It’s important to create variation within a garden so insects can protect themselves against extreme conditions. Hayes says this can be as simple as getting out a spade and creating a mound of earth, so that on hot days they have shady sides to keep cool. “That variation helps buffer species from the most extreme temperatures,” he says. A shaded slope relative to a sun-facing one can be 5C cooler. Under mature canopies of woodland you can get 10C cooler, says Hayes. “It really is a significant difference.” The bigger challenge is tackling the climate crisis to reduce the frequency of these extreme events. “We don’t need to stop climate change to save the butterflies. We need to stop climate change to save ourselves,” says Fox.