Unless you’ve been living in a cave, you’ll have noticed that this year’s warm and sunny summer weather has been a boon to butterflies. I’ve seen many species myself this summer in my own city centre garden, including large whites (Pieris brassicae), painted ladies (Cynthia cardui) and small tortoiseshell (Aglais urticae). Bees and hoverflies of many varieties are flocking to the overgrown fuchsia and almost-flowering ivy. But is this a sign that Ireland’s butterfly population is recovering, or is it just a small uptick in the decade-long decline?
The good news is that according to the data collected by volunteers as part of the Garden Butterfly Monitoring Scheme, recorded butterfly sightings are up by 83 per cent since last year. The bad news is that this encouraging figure must be set against the backdrop of last year’s dismal weather for butterflies and declines of over 70 per cent overall since 2008 when monitoring first started for most native species of whites and browns. While there are many drivers of this downward trend, the weather often has the last word. Last year’s poor summer was an additional misfortune for Ireland’s struggling pollinators and butterflies, on top of all the other challenges they face. Cool temperatures and rain limit the foraging ability of bees and butterflies and reduce the availability of food sources. Rain can even dilute nectar, making it less appealing and nutritious for bees, while cold temperatures restrict their flight activity, making it difficult to find and access flowers.
But it is no use blaming the weather when most of the damage to ecosystems is being carried out by us. The troubling decline in Ireland’s biodiversity is obvious to older people. In our cities, the presence of hungry gulls is a reminder that their marine food sources are dwindling. Rock pools in some coastal areas, once teeming with crab, shrimp and starfish, are sometimes no more than lifeless puddles. Elsewhere, the countryside is bare, and the air is empty of the swarms of flying insects common 40 or 50 years ago. Though there are still patches where nature thrives, the habitats that are vital for Ireland’s insects are deteriorating or simply unavailable.
Hedgerows are disappearing at a rate of up to 6,000km per year, according to Hedgerows Ireland; hay meadows are no more, and the widespread use of pesticides and fertilisers to create monocultures of ryegrass and Sitka Spruce make for inhospitable conditions for most other species. Invasive species, including the Harlequin ladybird, compound the habitat disturbance. Peatlands, wetlands and the limestone pavement habitats of the Burren are particularly important, but as recent National Parks and Wildlife Reports show, these habitats are often in poor condition, even where they are designated under EU law for protection. Ireland’s only listed butterfly species under the EU habitats directive, the marsh fritillary (Euphydryas aurinia), prefers boggy habitats that are either drying out or being destroyed for peat extraction. This all matters, because insects play a critical role as pollinators or as food for birds and other species. We simply cannot survive without them. Besides, they have as much right to the Earth as we do.
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A glance at the data collected under the national butterfly monitoring scheme shows that none of the 15 species monitored have shown an increase since 2008. The overall picture for Irish butterflies is “bleak”, according to the National Biodiversity Data Centre. To be serious about conserving butterflies, says expert Jesmond Harding, Government policies need to be much more ambitious in protecting their favoured habitats. Pollution, land-use changes and nitrogen deposition could all be factors in the decline of butterflies, but scientists need good data to determine why a species just disappears from an area in which it was previously recorded. The volunteers who have been painstakingly recording butterflies across the country play a vital role in gathering scientific data.
This year, citizen science is reporting that a couple of butterfly species are doing relatively well, including new inhabitants that have established in Ireland recently including the Essex skipper (Thymelicus lineola) and the comma (Polygonia c-album). The numbers of red admirals (Vanessa atalanta), small tortoiseshell and painted lady butterflies visiting gardens has increased noticeably over the last week or so. Butterfly conservation experts say that the season should peak before the end of August, so it is not too late to familiarise yourself with these beautiful visitors. Sign up to the NBDC mailing list to participate in the garden monitoring survey for next year.
A final tip: if you are lucky enough to have a small tortoiseshell come into your home to hide behind curtains or in a corner, it has not entered by accident. This beautiful creature is looking for a cool spot to hibernate for the winter, so instead of shooing it out again, give it a temporary home. Collect it gently and pop it into a lunch box lined with paper towel and – yes, really – put it into the fridge for the winter. Jesmond Harding collected 20 last year, and 15 of them survived when he released them in the spring.
Sadhbh O’Neill is an environmental and climate policy researcher
