Midsummer butterflies are already making their appearance in early May, thanks to a sunny spring which has led to what some are calling record-breaking conditions in the UK.
Typically seen in June and July, the Lulworth Skipper is now flying at Lulworth Cove in Dorset. In Scotland, Checker skippers have appeared earlier than usual, popping up in April instead of mid-May, while the first swallows typically show up around mid-June. In fact, one was spotted in Norfolk on May 1st.
“Checker skippers are like our calendar markers. They usually emerge between May 13th and 15th,” shared Tom Prescott, head of Butterfly Conservation Scotland. “So, seeing one on April 26th was quite a surprise for me.”
The Lepidoptera experts attribute these early appearances to the prolonged sunny and dry conditions but also warn that this may signal how insects are adapting to climate change.
While some species are emerging sooner, there’s a risk that these insects could become out of sync with their food sources or predators. “Sure, it’s great for checkered skippers, but I’m concerned for butterflies and moths that winter as eggs and need to synchronize their appearances with the budding leaves,” Prescott noted. For example, the rare Dark-bordered Beauty moth relies on smoke aspen, and if it comes out too early, it might find no leaves to eat.
This spring, many butterflies are appearing two to three weeks earlier than average. Generally, first swallow sightings over the last decade were around May 14th, but this year, it was spotted on May 1st at Norfolk Wildlife Trust’s Hickling Broad Nature Reserve.
Notably, the sightings of Swallowtail and Lulworth skippers on May 2nd marked the second earliest appearances in two decades, with 2011 also seeing an early spring. Back in the 1980s, Lulworth Skippers wouldn’t show up until early July.
The Marsh Fritillary was first seen in Wiltshire on April 20th this year, three weeks ahead of last year’s first sighting. This butterfly made its early flight through Devon and Dorset on April 9th.
These early butterfly sightings hint at the escalating pace of climate issues. Richard Fox, the head of science for Butterfly Conservation, remarked that timing their emergence is a significant challenge, but it’s something they will likely adapt to.
“There are genuine concerns about mismatches with host plants and other ecological factors,” Fox explained. “These biological systems respond to weather and climate changes over time but at differing rates.”
He added, “Populations of butterflies and moths vary a lot, so not every swallow will show up on May 1. If some emerge early, we might not face a crisis. There’s also room for evolutionary adaptations.”
Besides early sightings, there’s also evidence that butterflies are migrating north due to climate change.
Gatekeepers first crossed into Scotland last summer, while other species like White-letter Hairstreak, Comma, and Holly Blue are quickly moving north as well. The Holly Blue has been observed expanding its range from Edinburgh to Aberdeen, and Comma has reached the Highlands.
Last year marked one of the toughest for common butterflies since records began 50 years ago. Experts are hopeful that the sunny spring will help boost butterfly populations.
“Scotland has had a fantastic spring for butterflies,” Prescott remarked. “They are out for longer periods, and several species are rapidly heading north.”
