Poor weather clips wings of our butterflies
Butterfly numbers have plummeted across Northern Ireland following one of the worst summers on record.
Only the ringlet and green-veined white increased their numbers in a cold, wet season that saw most species show sharp declines, as revealed in the Big Butterfly Count.
Many of the big showy butterflies — such as peacocks and red admirals — didn’t appear until last week, taking advantage of a last burst of sun before autumn. Butterfly Conservation, which organised the survey, said heavy rainfall has put many already threatened species at risk.
“It took until July for the ground temperature to warm up enough for caterpillars to breed — that is what gives them their energy,” spokesperson Catherine Bertrand said.
“This was the last gasp of summer and the butterflies have been squeezed into this last week.”
Green veined white
Last year’s most common butterfly has been knocked off the top spot by the ringlet. This was one of just two successes this summer, increasing numbers by 12%. It may be thriving because people haven’t been cutting grass in the damp weather.
Six spot burnet moth
This colourful day-flying moth frequents flowery grassland, woodland and coast. Sightings have plummeted by 58% but more have been seen recently with September’s warm start. It prefers purple flowers such as knapweed and thistle.
The ringlet is this year’s biggest success story, bucking the downward trend with an 80% increase in sightings on last year. The butterfly, which thrives in long, rank grassy areas such as road verges, appears to do better in cooler conditions. Meanwhile the meadow brown, which flies the same habitat, has declined by 3%.
This butterfly can turn up anywhere, from city centres to mountain tops, and is one of our most successful. The small tortoiseshell has declined by 32% since last summer, but their emergence may have been held back by the poor conditions.
Just one peacock butterfly was reported during the Big Butterfly Count — a devastating decline of 96% on last year. Last summer large numbers emerged in the first week of August which was hot and sunny. The peacock needs very warm weather to emerge from the chrysalis and very few were seen until last week’s good spell.
Only seven sightings of this butterfly were recorded in this year’s Big Butterfly Count — a decline of 89%. This surprised experts because the winter was mild and red admirals hibernated, emerging to become one of the most common butterflies sighted in early spring. However, for some reason they did not go on to produce many caterpillars.
Everyone will recognise the caterpillars of this insect if they grow cabbages — so their 15% decline is good news for growers. Large and small whites have been held back by the cold, wet weather. The small white is down 43% from last year.