Four Devon butterfly species hit record lows as Dartmoor offers rare hope

Four butterfly species in Devon have recorded their worst numbers in at least a decade, according to new figures from Butterfly Conservation.

The Silver-washed Fritillary, Dark Green Fritillary, Wood White and Small Heath were all at their lowest levels in ten years. 

But on Dartmoor, the Marsh Fritillary showed signs of resilience, and one monitoring site on the edge of the moor recorded one of its strongest butterfly counts in recent years.

The figures come from the UK Butterfly Monitoring Scheme and Butterflies for the New Millennium, which are coordinated by the national charity Butterfly Conservation. 

The organisation recently reported that 2024 was the fifth-worst year for butterflies across the UK, with more than half of species now in long-term decline for the first time on record.

Pete Hurst, butterfly recorder for the Devon branch of Butterfly Conservation, compiled a snapshot of county data from ten well-known species.

He said: “Unfortunately, these figures show concerning drops in the numbers of beloved local butterfly species in Devon. This is in line with the national picture, and I would expect there to be similar reductions in other Devon species as well.”

The data showed 2024 was not only a poor year but significantly worse than any other since 2014 for several species:

• Silver-washed Fritillary numbers were 26 per cent lower than their previous worst year and 38 per cent below the ten-year average
• Dark Green Fritillary counts were 37 per cent lower than the next lowest and 60 per cent down on the ten-year average
• Wood White was 13.6 per cent below any earlier count and 99 per cent lower than the ten-year average
• Small Heath was down 67 per cent on its previous lowest year and 74 per cent down on the ten-year average

Mr Hurst said changing weather patterns and human activity were both to blame.

“We know that long spells of wet weather, which now seem to be happening more frequently, will have had a significant negative impact on last year’s showing of our butterflies, but there is much more at play.

“Sadly, we humans have destroyed wildlife habitats, polluted the environment and used pesticides on an industrial scale as well as changing the climate. That means that when we have poor weather, these already-depleted butterfly populations are highly vulnerable and can't bounce back like they once did, and with climate change, that unusual weather is becoming more and more usual.”

Some species did perform better. 

The Marsh Fritillary, which is found on Dartmoor, had its fourth-highest count in ten years. 

Mr Hurst said its caterpillars may be better able to withstand wet conditions.

Orange Tip and Holly Blue butterflies also did well in the spring. 

Gatekeeper and Meadow Brown were seen in good numbers in some areas over the summer.

Mr Hurst added: “My annual Wider Countryside Butterfly Survey square on the edge of Dartmoor actually had the second highest count of butterflies in the last six years with a high number of Gatekeepers, 53, and eight species of butterfly which is the highest in the last six years.”

More information about how to help butterflies can be found at butterfly-conservation.org.