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Butterfly Season Report

As I write this a snow clad landscape and low temperatures including-17.2 degrees Celsius in Mayo and -18 degrees Celsius in Tyrone is creating travel chaos and hardship for all life forms that remain active throughout the colder months. 2010 was bookended by snow and severe cold but the warmer months proved quite clement and accommodating for lepidoptera. March to June inclusive saw much dry, bright weather but hotter conditions arrived in mid-May and persisted into June. July August and September did not reach the sunny heights of May and June but were often dry while a benign October lengthened the flight season.

The tendency to produce very early records of butterfly activity noted in recent years was less pronounced in the early spring of 2010.The first and penultimate butterfly recorded in 2010 was the Small Tortoiseshell[17/01 and 24/11].Early records of Marsh Fritillary larvae were noted with records from mid-February. Early Painted Lady and Red Admiral records were made in March but it was not until much later that these butterflies were generally noticed. The first Brimstone recorded was seen on 21/03 while the earliest record for the Peacock was 07/04.The early spring records were generally later than those of recent years and this is probably linked with the cool conditions throughout spring but by April the longer daylight hours allowed for greater warmth which led to more butterfly activity. Butterflies soon made up for lost time with egg-laying by Brimstones in mid-April. A noteworthy early record was that of the Wood White [Leptidea sinapis] seen by Andrew Harding at Coolorta on 11/04.Other early records were of the Holly Blue, Small White, Green-veined White, Orange-tip and Green Hairstreak. First brood Wall Browns were found in Cork and Inishmeain on 17/04.The earliest records of the Small Blue, Common Blue, Small Copper and Large White were from coastal locations in Wexford and Dublin [Large White]. The earliest Dingy Skipper record was made in The Burren on 02/05 and the earliest Pearl-bordered Fritillary seen on the next day. Mid-May saw a mass emergence of the Pearl-bordered Fritillary with around 30 seen in a scrub clearing near Carron. By the second week in June numbers had dropped markedly with males scarce and only egg-laying females conspicuous. Good numbers of Common Blue, Réal’s Wood White, Green Hairstreak and Small Copper were in flight by May but it was the second brood of the Small Copper that was astonishingly numerous. Usually seen in ones and twos the butterfly had a bumper year; 67 were seen on 08/08 in an unimproved hay meadow in Meath. Early Dark Green Fritillaries were seen in Donegal [02/06] and Clare [05/06].The recent pattern of earlier emergence of the Large Heath continued with 11 seen in Donegal on 03/06. Meadow Brown [05/06] also continues to have earlier emergence dates with mid-June yielding the first recorded Ringlet [16/06]. The Marsh Fritillary was recorded first on 16/05 in The Burren and a number of new sites were found in several counties including Wicklow [first records since the mid-1980s], Cork, Limerick, Clare, Cavan and Leitrim. However many of these populations are located on proposed wind farm sites where road construction may be detrimental.

The Silver-washed Fritillary was first recorded on 20/06.The Irish distribution of our largest resident butterfly is probably increasing with the butterfly being found in newly maturing bog woodland and in developing scrub. A total was the 67 seen on 30/07 in Garryland Wood, Galway. The Hedge Brown first recorded was seen in Wexford on 11/07.The Small Heath first records were in mid-May [15/05, Donegal] and were numerous in Pollardstown Fen on 12/06 with 49 counted in wet fen. The Brown Hairstreak was first found on 25/07 and a significant time lag was noted in the emergences of the sexes. The first female on the site studied was not seen until 02/08; 7 days after the first males were seen. On 13/08 a peak count of 29 including 10 females was made at the Gortlecka site [Burren, Clare].By this date the males were worn while the females looked fresh. The females were feeding and basking but no egg-laying was observed. The males’ behaviour had altered; the basking and feeding of late July was replaced with mate-seeking behaviour.Younger males are sexually immature and days of feeding and basking are necessary before mating is possible. The females seen may have included mated individuals who were maturing their eggs. Holly Blue produced a sizeable second brood and seems to be recovering from its 2009 crash. The Wall is not enjoying the same upward trend and despite some high figures of 19 from Waterford and 15 from Howth, County Dublin numbers elsewhere remained low. It is hoped that the species is merely at the bottom of a population cycle and will soon recover. The Common Blue prospered during 2010 and John Lovatt reported astonishing numbers; one large bramble bush in Newbridge Park, County Dublin held over 100 individuals on 22/08.

The season’s final build-up during September saw large numbers of Small Tortoiseshell. The Peacock build-up precedes and somewhat overlaps with that of the Small Tortoiseshell but the latter are so noticeable because they congregate in flower-rich gardens during September. The Peacock did not produce large numbers in 2010 even on its favoured sites and this could reflect parasitism and/or the heavy rain during early July.

Our three newest species appear to have done well in 2010.The Essex Skipper was first noticed on 04/07 in Wexford where it is expanding its range. It continues to fly on a Kildare site it shares with the Small Skipper. The Small Skipper was first sighted on 02/07 [12 seen, including 2 females]. A peak of 39 was counted on 20/07.The last date it was searched for was 10/08 when 10 were counted along with 2 Essex Skippers. At least 11 Commas were seen in the Wexford area with the earliest on 22/04 and the latest on 05/10.

While I know of no records of larvae the fact that the Comma has been found each year of the last decade suggests residency.

Moths are more elusive and many nights that followed fine sunny days had clear skies and moth numbers at light traps were often low. Despite this some interesting finds were made. These are described in the accounts of our events.

I conclude by thanking all who record our butterflies with special mention of David Nash and the excellent ‘butterflyireland’ website run by the Dublin Naturalists’ Field Club.

Jesmond Harding 2010