It is not just Wimbledon fans and holidaymakers who have had enough of this British summer.
Naturalists have warned butterflies and other winged insects are having a very poor year, with some “seriously Awol” because of bad weather conditions.
There is typically a “June gap” each year where sightings of butterflies dip, when spring species such as peacock butterflies are no longer in flight and summer ones are yet to emerge.
However, cooler-than-average June temperatures have drastically exacerbated the effect this year. Even with decades-long declines in insect numbers, species that come out in summer including meadow browns, gatekeepers and ringlets can still be seen in the dozens or even hundreds in good habitats.
Data from the UK Butterfly Monitoring Scheme, which has involved people counting butterflies at about 3,000 sites since the 1970s, shows “very low” numbers of common blue butterflies. The first generation should be at its peak but few are being reported. The number of meadow brown butterfly sightings has also been very low.
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“What’s happening now is a delay of the summer stuff. It’s an elongated June gap. The gap has just extended, because the weather in June has been so cold,” said Dr Richard Fox, an ecologist at the charity Butterfly Conservation and the University of Exeter.
Matthew Oates, a former National Trust adviser who writes The Times’s Nature Notebook column, said most butterflies were having a very poor year. But he said it was not just butterflies experiencing a bad summer. “There’s a severe paucity of winged insects in general, including the biting flies — how many people have been bitten by mosquitoes this summer? Late June’s mini-heatwave failed to generate massive hatches of insects, nice or nasty.”
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Bumblebees are between broods, crickets and grasshoppers are very late, although a few insects including dragonflies and damselflies are coping, he said.
“But loads are seriously Awol, notably the aphid-feeding hoverflies — the common flower fly should be humming in mid-air above us, but I’ve seen only one all summer. Hoverflies are important pollinators, and there are loads whose larvae are predators of aphids, like ladybird larvae, which are also Awol,” Oates said.
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Cooler weather slows the process of butterflies going through metamorphosis from a caterpillar into a butterfly. When they do emerge, lower temperatures are also bad news for their efforts to reproduce, slowing down their efforts to fly around and find mates, or for females to locate the right plants to lay their eggs on.
“If it’s cold then what they’re doing is roosting, sleeping in trees, bushes and grass tussocks, and they’re not reproducing. They have a finite lifespan, so less time to reproduce means fewer eggs and fewer offspring they’ll give rise to,” Fox said.
Grahame Madge, an amateur naturalist who has watched butterflies for more than 50 years, said: “This year so far has been remarkable in that even familiar species are notably absent. Large and small whites are usually flyby species and ones you should see almost every time you look out of the window. I have a butterfly bush outside my back door which is bereft of its namesakes,” he said.
The absence of butterflies appears to be a weather-induced blip, rather than something more serious. “It’s not necessarily insect armageddon. Last year we had a spring that wasn’t particularly good for insects and in late May people were having similar conversations — have we reached a tipping point? Have the insects gone? Then June was lovely last year and suddenly there were insects everywhere,” Fox said.
He said he was mindful that a return of warmth could turn things around this year too. “But if the weather doesn’t perk up, this could go down as a really poor year for butterflies that would have knock-on effects for several future generations of butterflies,” he added. The public are invited to count butterflies from Friday as part of the Big Butterfly Count, a citizen science scheme.
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Separately, England and Northern Ireland’s environmental watchdog has launched an investigation into the previous government’s repeated emergency authorisation for farmers to use thiamethoxam, an insecticide linked to bee deaths. Labour has promised to ban the pesticide and not to repeat such emergency approvals to help sugar beet crops.
