Once you have entered the mysterious, magical world of moths, there’s no going back. It is very easy to overlook moths, many of which hide away by day and only venture out under cover of darkness. But once you take a peep into their secret lives and discover their extraordinary beauty and diversity, their amazing lifecycles, their incredible powers of camouflage and mimicry, the phenomenal migrations… that’s it, you’re hooked. You have a become a moth-er.
Mothing – finding and studying moths – is addictive. Moths are such beautiful, fascinating creatures, and each find brings a new thrill – you never know what you will discover next.
When we arrived on Rathlin Island, we couldn’t wait to see what moth species live here. Throughout the year, we tried a variety of special techniques for finding these mysterious creatures. We deployed light traps at night to attract moths whenever the weather allowed (here on Rathlin that can be frustratingly infrequent!). As there are some species that are not attracted to light, we also went out after dark to search flowers for feeding moths and watched out for day-flying species as we walked around the island. We even experimented with using sugary baits and luring them with special moth pheromones, though neither of those proved successful.
When the weather was settled enough to plan mothing in advance, we invited Rathlin locals and visitors to come along for a mothing morning, to join us as we opened up the trap to see what had arrived overnight.
Wherever you live, there is usually a remarkable diversity of moth species to be found, but we were delighted to discover that Rathlin is a particularly good mothing location. Despite being a small island, Rathlin has a good diversity of natural habitats including coastal heaths, wetlands, wild flower meadows and sea cliffs. The varied vegetation in these habitats supports a wide range of insect species, some of which are highly specialised to living on particular plants. In addition, Rathlin has plenty of plants that have been brought to the island by people, like the conifer plantation, and many other trees, shrubs and flowers planted in gardens. These may be less ‘natural’ habitats, but they are nevertheless great for Rathlin’s moth diversity.
In this blog post, we will run through some of our mothing highlights of 2017. We’ll concentrate only on the ‘macro moths’ – a commonly used but not strictly scientific term that (in general) includes only the larger and (often) more easily identified species. The enormous number of smaller species – the ‘micro moths’ – have always been considered a more difficult group to identify and have often been ignored altogether. We have been making a considerable effort to record the micro moths of Rathlin as well, but they will be the subject of another post later in the year.
The moths of Rathlin have been studied before, albeit rather intermittently. In fact, the island macro moth list already stood at about 205 species before we arrived, and this included a number of rare and very localised species. We knew what species to expect and identified a few target species to look out for, thanks to the generous help and advice offered by the Northern Ireland moth recorders and other local moth-ers, and the information in the The Butterflies and Moths of Northern Ireland (a spectacularly thorough and beautiful book!). But it had been a few years since any serious trapping had been done, so we were excited to see what we could find, and even hoped to add some species to the Rathlin moth list.
Now, let’s rewind to spring 2017 to begin our look back at the year’s best mothing moments.
It didn’t take too long for us to get a Rathlin first. On 7th May we had three Red-Green Carpets in our trap, and were surprised to find that the species had not been seen on the island before. It doesn’t seem to be a common species on the north coast of Ireland, but appears reasonably numerous on Rathlin. In fact, we found several more in November. We guess it had not been caught here before simply because very little moth trapping has been done in the late autumn to spring period.
On 18th May we caught two more new-for-Rathlin species: Shoulder Stripe and Herald. Both of these appear to be generally scarce on the north coast, and were not particularly expected on the island. Neither species was seen again all year, so presumably they are not common here. However, Shoulder Stripe flies mainly in the early spring and we will need to do more trapping at that time of year to find out its true status.
A week later we found a species we had been really hoping for: Netted Pug. This is a rare coastal species in Ireland and, although it had been found on Rathlin before, the last record was in 1971 and all subsequent attempts to find it had been unsuccessful. We were delighted to find one in our trap on 25th May, and quite astonished when, four days later, we discovered two of them on the outside of a toilet window at the West Light. The toilet light had been left on overnight, and had attracted these rather special moths. Sometimes the best finds happen when you’re not even trying!
Incredibly, on 11th June, the very same lucky toilet window scored a new species for Rathlin. This time it was a Thyme Pug, a moth which is scarce and very localised in Northern Ireland, although the cliff top habitat on Rathlin is ideal and has plenty of its eponymous foodplant. From then on, we made it our first job every day to check that toilet window!
A Green Silver-lines was a colourful surprise in our moth trap on 27th May. Typically a woodland species that is closely associated with oak, we would not have expected to add this one to the Rathlin list. There is almost no oak on the island, so exactly what this beautiful insect was doing here is a bit of a mystery.
On 2nd June, while we were working at the West Light Seabird Centre in the middle of the day, a Hummingbird Hawkmoth flew in through the open back door and proceeded to fly madly around the room until it was captured against a window. This is always an exciting migrant species to see and, even though it was not a first for Rathlin, it was a rare chance to examine this extraordinary insect up close.
During a very productive period in mid June we added another five species to the island list. A Bordered White on the 14th was unexpected, although the island’s conifer plantation may provide suitable habitat. We did catch the species one more time during the year, although that was at the West Lighthouse quite some distance away from the conifers. Also on the 14th was a surprising Marbled White Spot. This seems to be a rare moth in Northern Ireland, known from only a handful of locations and, although suitable heathland may exist on Rathlin, we didn’t find any more of these moths during the year.
18th June was equally successful, with Clouded Border and Miller both new for the island. Clouded Border is fairly ubiquitous in Northern Ireland and it is surprising that it had never been found on Rathlin before, although we did only catch one more of them later in the summer. Miller is much scarcer in Northern Ireland, especially on the north coast, and was therefore quite an unexpected find here.
Also on the 18th, a Chestnut-coloured Carpet was in our trap at Kebble. Rathlin is the only known site in Northern Ireland for this scarce juniper specialist, so it was a very pleasing find. We didn’t see this species again all summer, suggesting that even here it is not common. In 2018 we will aim to target areas with juniper to investigate the status of this and other juniper lovers.
On 22nd June we found another of our target species by the subtle entomological technique of charging frantically after it through marsh and waist-high rushes. The flying insect eventually settled for long enough to confirm its identity as a Grass Rivulet, a species that had been recorded on Rathlin previously, but not since the 1930s! It was good to confirm it still living here, and it actually seems to be doing quite well as on 5th July we caught nine of them in a single trap. The larvae of Grass Rivulet feed only on yellow rattle, which appears to be very common in the island’s hay meadows.
A Brussels Lace in our trap on 29th June was another new species for Rathlin, but our encounter with it was bittersweet. Upon release, this moth flew underneath the garden picnic table and settled in a dark crevice, where we assumed it would be secluded enough to hide away safely until nightfall. However, a brazen and opportunistic Chaffinch came hopping along and we watched in horror from the sitting room window as it pounced on the Brussels Lace and gobbled it down, without a thought for its delicate beauty or its important contribution to the Rathlin moth list. The Chaffinch will forever be regarded as Fringilla non grata during all mothing activities. In fact, due to the local abundance of voracious garden birds we now release most moths on nightfall, after all the hungry hordes have gone to roost.
A hat-trick of new-for-Rathlin moths on 5th July partly made up for the traumatic events of late June. A Small Elephant Hawkmoth in the trap was an attractive but perhaps not entirely surprising addition to the list, while a Clouded Buff was an excellent and highly noteworthy record. This is one of Northern Ireland’s rarest moths, known from just a few locations, so it was a very significant addition to Rathlin’s list.
Two firsts in our trap was a pretty good start to the day, but the excitement continued after lunch. A small brown moth seen fluttering along the coast at Bull Point was pursued on foot along the precipitous cliff-edge until it was finally captured in a specimen pot for identification. On examination it proved to be a Marsh Pug, a species that had been rarely recorded in Northern Ireland at all, and certainly never before on Rathlin. Its appearance on the island is puzzling as its main food, field mouse-ear, is unknown here. Perhaps it was a migrant that had wandered over to Rathlin from somewhere else, but who knows where that might be?
Bordered Grey was our next big highlight on 2nd August. This is another of Rathlin’s real speciality moths, as the island is one of only two sites in Northern Ireland where it is known to occur (the other is Peatlands Park, Co Armagh). The Rathlin population was only discovered in 2001, and we were glad to prove the species still persisting here 16 years later, even if we did only manage to find a single individual.
A Buff Footman on 21st August caused us some excitement when we checked the books and read that it is extremely rare in Northern Ireland. However, we soon learned that the species has recently undergone an incredible population explosion throughout the country and is now found almost everywhere. Nevertheless, it was a the first ever record on Rathlin so we were still pleased with the discovery.
The weather in early autumn was mostly too terrible to have the traps out, but we did discover that searching sheltered ragwort flowers after dark was quite a productive way to find feeding moths. We found quite a number of species by this method (although nothing especially rare), and it was an enjoyable way to see moths and other invertebrates going about their secret night-time business.
By the end of autumn relatively very few moths are on the wing, but we spent a bit of time searching fuchsia bushes after dark and came across a few hardy insects feeding on the flowers. A Pearly Underwing on 14th November was an excellent reward for our nocturnal efforts, and was just the second ever sighting for Rathlin. This is a scarce migrant species in Northern Ireland that has only rarely been recorded on the north coast.
Our very last moth of the year was yet another new species for the island. On a damp and breezy night on 20th November when we would hardly have expected any sensible moths to be out and about, we found a Dotted Border by the roadside, clinging on tight to some tall plant stems against the wind. This is a reasonably common moth in Northern Ireland, but was not previously known from Rathlin. Even though it is a winter-flying species, they are not normally on the wing until at least late December, so the date of our sighting seems to be quite unusual.
And so, with that final Dotted Border, our mothing year drew to a close. We have only featured the very best bits here, and have had to leave many other interesting sightings out. During 2017 we managed to find and identify 150 species of macro moth on Rathlin. This included 15 that had never been recorded here before, taking the island’s all-time macro moth list to 220 species. Even so, we can be sure that there are still plenty more to be discovered here. There has been little trapping conducted on Rathlin in the early spring, and some habitats and locations have never been surveyed, so there is lots of potential for more magic mothing moments in 2018!