The first butterfly reported to Butterfly Conservation Ireland in 2020 is a Peacock near Minane Bridge, County Cork on February 27th. The butterfly in this photo was seen on March 5th in the same area. The Peacock in this photograph is clearly in need of warmth. It is basking on a rock, absorbing heat mainly from the surface of the rock. It obtains a minority of the heat from the direct sun shining on its upper wing surfaces.
In early spring, Peacocks rarely spend long in the open. The butterfly basks and feeds, remaining close to its hibernation site. When it gets cool, the butterfly will return to its resting place. It will not stray far until there are some days of sustained warmth and sunshine. When conditions become consistently warmer, the Peacock departs to find food and breeding sites.
Good areas to look for Peacocks during March are sunny rides and clearings in woodland. When the days lengthen, the Peacock will be found in more open areas where it can be found in company with its close relative, the Small Tortoiseshell, another butterfly that passes the coldest months as an adult.
The appearance of these colourful butterflies is a great tonic after a bleak and tempestuous winter. To help them, allow your willow to flower, do not cut flowering dandelions and provide extra nectar in the form of native primroses and non-native flowers such as grape hyacinth Muscari neglectum. Nettle patches should be allowed to develop in warm, sunny areas to encourage breeding.
Finally, let us know of your sightings by emailing us at conservation.butterfly@gmail.com with the following information:
your name/s,
date of the find,
species found,
the life stage/s found,
numbers seen,
location the butterfly/moth was found (e.g. townland name, site name, county),
six-figure grid reference, including the letter identifying the 100,000-metre grid square in which the location lies (see https://irish.gridreferencefinder.com or Discovery Series maps)
weather conditions
and any other interesting comments you wish to provide.
Example: John Smith, 14/06/12, 14 Small Blues, 15 Small Heaths, Portrane sand dunes, O254515, County Dublin. Small Blues feeding on Kidney Vetch and Creeping Thistle. Sunny, light breeze, around 18 degrees Celcius.
It will be greatly appreciated if you are sending in your records of several species by listing the butterflies observed in the following order:
Small Skipper, Essex Skipper, Dingy Skipper, Common Swallowtail, Wood White, Cryptic Wood White, Clouded Yellow, Brimstone, Large White, Small White, Green-veined White, Orange-tip, Green Hairstreak, Brown Hairstreak, Purple Hairstreak, Small Copper, Small Blue, Common Blue, Holly Blue, Red Admiral, Painted Lady, Small Tortoiseshell, Peacock, Comma, Pearl-bordered Fritillary, Dark Green Fritillary, Silver-washed Fritillary, Marsh Fritillary, Speckled Wood, Wall Brown, Grayling, Hedge Brown/Gatekeeper, Meadow Brown, Ringlet, Small Heath, Large Heath, Monarch.
These records will contribute to a national butterfly atlas which will cover the period 2017-2021. This should provide a clearer indication of how Ireland’s butterflies are performing in an era of profound change.
A slate grey sky, sharp persistent westerly wind with the threat of a deluge usually discourages outdoor effort but not for our optimistic and committed members. And as for rain, it stayed dry throughout our workday.
We targetted an area of scrub that we knew contained some fine specimens of Alder Buckthorn. If we could clear the surrounding scrub we would make the Alder Buckthorn available for breeding by Brimstone and Holly Blue butterflies as well as the range of bees that are obsessed by the unexpectedly rich nectar the plant’s tiny flowers provide.
A great effort was made. Five hours later we had a great clearing made. We kept sufficient scrub to give shelter to the buckthorns while allowing light to reach the area. An old pond, which I last saw around 20 years ago, was still there. Perhaps the frogs will return to breed there in the next few weeks.
Another butterfly that we hope will benefit from our work is the Dark Green Fritillary, which is very rare in Kildare, Meath and many other counties, especially counties lacking a coast. The violets in the clearings which grow in patches among dry grass leaf litter offer promising breeding opportunities to this dynamic, beautiful butterfly. We’ll see if this happens in June/July!
Thanks to all who braved the elements. There is strong camaraderie on our workdays with conversation and lunch making the work so much sweeter!
An Alder Buckthorn plant now available for the Brimstone butterfly.A cleared area at Lullybeg, County Kildare.
At this time of year, day-length is increasing and the angle of the sunlight is reaching further indoors. The light is reaching tucked-up butterflies, rousing them and causing them to appear at windows.
No matter how energetic the butterflies are as they toss themselves against the glass, it is not the time for their release. It is bitterly cold, wet and occasionally stormy this February and there have been no records of wild free-flying butterflies so far this year. This weather may continue into March.
Place any butterfly that has awoken in your home in a glass jar, lined with a kitchen roll. You can place more than one butterfly in the jar. Place in the fridge and release only when there is a warm, settled spell, usually from late March. I have over-wintered a Small Tortoiseshell until mid-May. It flew energetically away, apparently none the worse for its extended rest.
Not all butterflies survive, even when the recommended measures are used. It is likely that these casualties arise from insufficient weight gain pre-winter or loss of weight during the winter when fat reserves are wasted flying indoors for a prolonged period.
Owing to the volume of inquiries this winter, we will advise when to release the butterflies.
Here is a photograph of two Small Tortoiseshells on kitchen roll in a glass jar that I am over-wintering in my fridge where the temperature of four Celsius is ideal to keep them dormant.
Small Tortoiseshells being over-wintered in the fridge in a glass jar with the lid removed for this photograph. Line the base of the jar with kitchen roll for the butterfly to perch on and to absorb any excess moisture. Photo J. Harding.
From the state of Michoacán in Mexico comes the sad and disturbing news of the violent deaths of two butterfly guides, Homero Gómez and Raúl Hernández who were protecting the Oyamel fir forest habitat of over-wintering Monarch butterflies.
The Oyamel fir forest is a Monarch butterfly forest located in part of Michoacan, Mexico and Mexico City, Mexico. Billions of butterflies migrate from Canada and the United States to Mexico to hibernate during the winter. The clusters of Monarch butterflies bedecking tall forest trees with their orange wings is one of the greatest natural sights on Earth. Their migration constitutes “70% of the total overwintering population of the Monarch butterfly’s eastern population” (UNESCO, 2013), becoming one of the most dramatic and spectacular migrations of all insects. The monarch butterfly has an important value to the environment and the culture. Because of the number of Monarch Butterflies migrating, they are one of the greatest pollinators in America (Taylor, 2009).
Oyamel fir forest has been illegally logged, therefore the ecosystems and the Monarch butterflies are under threat. The World Wildlife Fund data reveals that “[a]ccording to a survey carried out during the 2012-2013 winter season by the WWF-Telcel Alliance, and Mexico’s National Commission of Protected Areas (CONAP), the nine hibernating colonies occupy a total area of 2.94 acres of forest—representing a 59% decrease from the 2011-2012 survey of 7.14 acres. The migration of these insects is endangered to extinction threatening the equilibrium of the continent’s environment.
Homero Gómez, one of best-known guardians of the monarch butterfly in Mexico and a leader of the ejido (a Mexican cooperative system of community and shared ownership) disappeared on January 13. Mr Gómez’s body was found in a well on 29 January. The state attorney has stated that the death was an accident. Officials initially said his body showed no signs of violence, but a post mortem examination revealed he had suffered a blow to the head before drowning in the well.
However, a second guide, Raúl Hernández, 44, disappeared on Monday 27 January. His body was found six days later at the top of a hill in the El Campanario Monarch butterfly sanctuary. Forensic experts said his body was covered in bruises and he had a deep wound to his head. An investigation into his death is underway.
Conservationists fear his death may be linked to that of Homero Gómez. Gómez’s family said that prior to his disappearance, the activist had received threats warning him to stop his campaign against illegal logging.
He was a tireless campaigner for the conservation of the Monarch and the pine and fir forests where it hibernates. The sanctuary he managed opened in November as part of a strategy to stop illegal logging in the area, which is a key habitat for the species. He was also involved in reafforestation.
Mexico has serious corruption and criminality problems. In 2019 there were 34,582 recorded killings, the highest rate ever. In Michoacán 53 police officers were detained recently by prosecutors in connection with the disappearance of Gómez. The justice system in Mexico allows offences to go unpunished, with only 3% of murders in Michoacán state solved.
This background of corruption and violence makes the conservation work of Gómez and his community all the more remarkable. He knew his life was under threat yet he refused to be intimidated. Homeo was committed to saving the hibernation habitat of the Monarch and his community’s environment.
At Homero Gómez’s funeral, a handful of monarch butterflies flew into the church in Ocampo and fluttered above the congregation. In Mexican culture, the monarch is considered the soul of the recently departed as its annual return to Mexico coincides with Day of the Dead on 2 November.
His son, also named Homero, says that Homero Gómez firmly held that belief too: “We know he will return in the form of millions of butterflies in November.”
The site management day planned for Fahee North, County Clare on Saturday 15th February has been postponed due to the adverse weather forecast for the weekend. The event will be held in September. Details of the new date will be posted on the Events page when known.
Butterfly Conservation Ireland regrets any inconvenience caused. We hope you can join us in good weather in September.
WHERE DID OUR BUTTERFLIES LIVE WHEN IRELAND WAS COVERED IN DENSE FOREST?
Most of Ireland’s butterfly species and many moths breed on grasslands. Only one shade-tolerant butterfly, the Speckled Wood, can breed on foodplants growing in shady conditions. Even species that breed in woods do not breed under the heavy shade where it is too dark and cold to support larvae.
In the wildwood that blanketed Ireland, how did these species survive?
The pollen record shows that Ireland had tundra vegetation for around 1,000 years after the most recent glacial period which ended 11,000 years ago. Stunted willow and grasses occurred and arctic wildflowers like Mountain Avens flowered in brief arctic summers. Around 10,000 years ago the climate warmed. A succession of shrubs and early colonising tree species appeared, especially juniper and birch. Around 9,000 years ago Common Hazel and Scots Pine appeared and dominated for around 3,000 years. From 8,000-6,000 years ago, oak and elm with ash and yew developed. The first farmers appeared about 6,000 years ago. From 4,500 years ago the first major human impact on the country’s forests began to become evident. By the Early Christian period, around 1,500 years ago, the impact was very evident and by early Medieval times, very little woodland remained.
However, thousands of years of dense, countrywide woodland cover would have made Ireland totally unsuitable for almost all of Ireland’s butterflies-probably only the Purple Hairstreak would have survived in closed-canopy woodland. How, then, did Ireland’s grassland butterflies survive? The answer that has been advanced is that their populations would have been very low, confined to areas that trees could not grow, such as bogs, unstable sand dunes, river banks and on thin soils in upland areas. This view is borne of the necessity to explain how the butterflies survived rather than the suitability of these habitats for the range of species that occur today. Lightning strikes that burned woodland and generated grassland mixed with early successional woodland habitats have also been suggested as providing the habitat needed for survival.
Recently, the view that the post-glacial landscape of Ireland and temperate-zone Europe was heavily wooded has been challenged. Dutch ecologist Dr Frans Vera’s book Grazing Ecology and Forest History (translated into English in 2000) provides an insight into what woods may have looked like. The picture he paints is intriguing. If accurate, it would explain a great deal about how butterflies, moths and many other invertebrates manage to exist in Ireland, Britain and in temperate Europe.
Vera puts forward the view that the landscape was far more open than many believe. Temperate zone Europe, Vera maintains, would have been characterised not by ubiquitous species-poor closed-canopy forest – as is commonly thought – but by a more open form of wood-pasture driven by grazing animals. Europe would, for the most part, have been a dynamic, shifting landscape of open-grown trees, emerging scrub, grazing lawns, groves and thorny thickets. An open wooded landscape like this, with grassy areas forming large clearings, would be ideal habitat mosaic for our butterflies. Butterflies and moths really like the warmth and shelter of wood edges, rides and clearings. Even the bog specialist, the Large Heath, will breed on a bog with scattered trees and scrub.
Vera argues that Europe had a large population of animals such as Beavers, Red and Roe Deer, Elk, Wisent and Wild Boar-similar to the population sizes seen in Africa today. These animals created open areas by trampling, digging, grazing, browsing, de-barking, felling trees and damming rivers (Beavers).
While there are debates and challenges regarding Vera’s theories, there is evidence that he may be accurate about the type of landscape that may have existed before human impact became important.
SAPROXYLIC BEETLES
Dr Keith Alexander, an independent specialist in saproxylic beetles (invertebrates that are dependent on dead or decaying wood (or dependent on other organisms that are themselves dependent on dead wood)), argues that sub-fossil saproxylic beetle evidence has been interpreted – wrongly – to describe a landscape that was, in the past, predominantly closed-canopy forest. In his view, the beetle evidence – when properly analysed – clearly shows the opposite: a landscape characterised by open-grown trees.
For example, species like Dryophthorus corticalis and Prostomis mandibularis, one of the commonest beetles of the Early Holocene (12,000-7,000 years ago), are highly specific and require large girth tree trunks containing volumes of decayed heartwood. Closed canopy conditions do not produce such trees.
Overall, says Alexander, sub-fossil evidence for the early Holocene indicates that 28% of the sub-fossil beetle fauna were grassland and scrub species; 13% arboreal; and 47% wood decay. In the late Holocene, 44% were grassland & scrub species; 11% arboreal; and 34% wood decay. The composition shows very low levels of shade-demanding arboreal species – so while trees are well-represented, shade is clearly scarce. The Late Holocene records indicate increased open grassland and scrub, as well as the presence of early successional mosaic species, which would be expected as humans re-colonised the land and agriculture developed. For both the Early and Late Holocene, predominant open wood pasture is consistent with the data; the closed-canopy forest is not.
CHALK GRASSLAND SNAILS
A similar picture emerges from the fossil evidence of chalk grassland snails. In the late 1990s, just as Vera was completing his thesis, environmental archaeologist and conchologist Dr Mike Allen, a lecturer at Oxford University and research fellow at Bournemouth University, began questioning the prevailing archaeological belief that the chalk grasslands around Stonehenge, Avebury, Dorchester and Cranborne Chase in Wessex were blanketed in postglacial woodland.
The sub-fossil snail record, Allen realised, pointed, instead, to a landscape of open grassland with open-grown fruiting trees and shrubs. It is his work that has informed the stunning visual displays depicting the evolution of the chalk landscape in the new museum at Stonehenge. Herds of grazing and browsing animals kept these savannahs (a savannah is a mixed woodland-grassland ecosystem with an open canopy that allows sufficient light to reach the ground to support an unbroken herbaceous layer consisting primarily of grasses) open, providing habitat for the snails; and it was this open landscape supporting a huge biomass of animals that attracted the early human populations to the area.
LICHENS
The lichenologist Dr Francis Rose, a former lecturer at King’s College, London, had scratched his head over closed-canopy theory from the 1970s until his death in 2006. His work is largely concerned with epiphyte forest lichens and for thirty years he studied them, in particular, in the New Forest (Hampshire, southern England). He noticed that very few species of lichen – or, indeed, mosses or liverworts – could be found inside dense stands of trees. Almost all require light and are found on either open-grown trees or trees along rides and the edges of glades or ‘lawns’.
The survival of relict species of moss and arctic-alpine plants – typical of the habitat of the last glacial period (i.e. before trees returned to our landscape with the warming climate) – on common land in Denmark grazed by horses also convinced Rose of the role of herbivores in keeping areas open of tree cover. Similar Devensian/Midlandian era (last glacial period) habitats in Norfolk, he noted, were vanishing with the abandonment of traditional grazing, and small fen plants like northern bog sedge and butterwort, and various orchids and subarctic type bryophytes were disappearing with them.
CONCLUSIONS AND IMPLICATIONS FOR OUR BUTTERFLY POPULATIONS
While Vera’s views have been challenged there is no doubt that such a situation of open woodland is beneficial to butterflies. Grazing by large herbivores is very important for the maintenance of these habitats and many butterflies would disappear if grazing ceased. Grassland butterflies in Ireland generally dislike large, unsheltered open areas even when these grasslands contain an abundance of nectar and larval foodplants. In such species-rich grasslands, it is among scrub that large butterfly populations will be found.
A butterfly gardener should take account of the value of maintaining a range of habitat types in an area, with native, mature, open woodland, dense scrub patches, scattered scrub and trees, open exposed ground and flower-rich grassy areas throughout. For a re-wilding project, native grazers, as well as domestic livestock, reintroduced Wild Boar and Beaver may be ideal to restore the landscape to something resembling its state before humans burned and felled woodland.
Winter is a time of meagre fare for butterfly and moth lovers. Sometimes we give up on our passion altogether for this season at least and yearn for warmth’s return, for Emperor moths, Orange-tips and Holly Blues to fly from March onwards.
Yet stirring in the darkness unbeknown to most exist a few select hardy winter moths. These occasionally come to outdoor lights. All three pictured here came to my outdoor light. On milder nights these seek out mates and breeding sites. There are some benefits to flying in winter. Bats, the scourge of nocturnal moths are safely out of the way, in deep sleep. There are far fewer insect predators to trouble moths. There are fewer insectivorous birds foraging in hedges and woods in daylight hours for resting moths.
These moths do not need to place their eggs on growing leaves. All breed on native trees, placing their eggs on or close to leaf buds or on the bark. The three moths, the December Moth, Winter Moth and Mottled Umber are flying now. The females of the latter two are flightless and simply wait on our beside the cocoon from which they emerged to be located by a male. Soon she lays her batch of eggs and expires, her job done.
Their eggs will hatch in April when the buds open. These will be a great feast for breeding birds who time egg-laying and hatching in synchrony with the availability of the soft, juicy, protein-rich larvae. Enough survives to pupate in June where they will await the onset of cold weather to hatch as adults.
Although winter is a vast empty space for many butterfly lovers especially after the excitement of Christmas has passed and we feel ready for spring only for weeks more winter to cast its colour-drained pall, winter moths offer just a little consolation. Sombre as December weather, they are a fitting complement to the shadowland that is winter.
December moth, male on a limestone wall, December 2019.This male Mottled Umber fluttered into the hall, initially attracted by the outdoor light.A male Winter moth found beneath the outdoor light above my front door. Many individuals are paler than this specimen. This moth is frequently attracted to windows when the light is on.
Winter Moths
Sharp winter light slants morning and afternoon
Dank vapour turns all cold blue
Short daylight and long night lonely under the moon
Little to see, less to do, fast time’s slow winter passage to rue.
But huddled close by the outdoor light
A furred, maned December moth
Braves a shivering winter night
Unmoved while light glows, a Sloth.
Fluttering before relaxing on his brightened masonry bed
A Mottled Umber, charcoal or brown on rust or cream
Blends on bark or stone, wings reflect an arrowhead
Vague and defined the impressionists’ dream.
Windows lit from inside casts the outside in darker night
Winter moth mirage, pale and plain,
A sylph of the dark yet a lover of glassy light
Like a wet birch leaf he clings to the pane.
His female patient on cocoon waits for mate and doom.
A study published in 2018 (cited as Kurze, S., Heinken, T. & Fartmann, T. Oecologia (2018) 188: 1227. https://doi.org/10.1007/s00442-018-4266-4) has found that nitrogen enrichment in caterpillar host plants increases the mortality of common Lepidoptera species.
The study involved testing the response of larvae of five common butterfly and moth species to host-plant fertilization using fertilizer quantities usually applied in agriculture. The species involved are Small Heath, Speckled Wood, Small Copper, Sooty Copper (not found in Ireland or Britain) and two moths, Straw Dot and Blood Vein.
Nitrogen fertiliser was applied to two host plant species, Annual Meadow Grass used by Small Heath, Speckled Wood and Straw Dot and Sheep’s Sorrell used by the Small Copper, Sooty Copper and Blood Vein.
Nitrogen fertiliser kills caterpillars
The researchers found that the addition of nitrogen decreased the survival of all six species by at least one-third. Richard Fox of Butterfly Conservation UK commented that increases in larval mortality range from 33%-80%. This study presents the first evidence that current fertilization quantities in agriculture exceed the physiological tolerance of common Lepidoptera species. The results suggest that (1) the negative effect of plant fertilization on Lepidoptera has previously been underestimated and (2) that it contributes to the range-wide decline of Lepidoptera.
There are further issues that arise from the study. The situation may be considerably worse than the study found. Applying 90 kg of nitrogen per hectare per year as was done for the study would be likely to remove Sheep’s Sorrel and Annual Meadow Grass from agricultural grassland altogether. The reason for this is that these caterpillar host plants will be out-competed by coarser, aggressive plants that respond to increased nitrogen by growing at a fast rate. Even if this is not the case the increased fertility produces a greener, lusher sward where temperatures are lower, delaying or even preventing larval development. In addition, nectar resources for adults are usually lower than required as grasses out-compete nectar-rich flora.
Furthermore, while application rates of nitrogen on grazing land in Ireland varies, 120 kg of nitrogen per hectare is often applied. It is highly unlikely that the Small Heath or Small Copper can survive on these grasslands. Teagasc, the state agency providing research, advisory and education in agriculture, horticulture, food and rural development in Ireland advises farmers on nitrogen application rates. For dairy grazing, these can rise to 210 kg of nitrogen per hectare per year.
Under such an application regime it is no surprise that butterfly and moth species are being eliminated from the landscape, or why such formerly widespread and abundant species like the Small Heath and Wall Brown are now in serious trouble.
Research needed to save farmland butterflies
Research should be carried out to determine the rate of nitrogen application that grassland Lepidoptera species can tolerate. The Sooty Copper was able to cope with 30 kg of nitrogen but the other species studied were not assessed for nitrogen tolerance. A study of biodiversity richness under the full range of nitrogen inputs it advises (including nitrogen added by slurry applications) should also be undertaken by Teagasc. Nitrogen application should be reduced or prohibited on farmland adjoining land designated as Special Areas of Conservation and National Heritage Areas to ensure these areas are not contaminated.
This issue can be addressed. Forcing land to produce more food by pouring chemicals into the soil cannot continue at the expense of biodiversity, water quality and possibly animal and human health and our world in general. Butterfly Conservation Ireland will take up the issue with Teagasc and urge the organisation to undertake the research needed to assess the impacts of nitrogen application on biodiversity on Irish farmland and alleviation and amelioration strategies. Good farming and good wildlife conservation must be the outcome if wildlife is to survive in today’s farmed landscape.
Last Autumn we were contacted by Peter Cunningham from Westmeath – about a special exhibition of butterfly-themed art launching in early October in the parish of Drumraney County Westmeath.
Peter explained that he and fellow parishioner Christy Grimes were arranging an exhibition of artworks by three disabled artists from the UK – Christine Bielby, William Birch and Elaine Garsden. The artists are keen butterfly enthusiasts and wished to donate all proceeds from the exhibition to Butterfly Conservation Ireland. I was honoured to attend the exhibition on behalf of BCI – to meet the three artists and their carer Linda Lord – and the many people of Drumraney parish who attended and supported the exhibition on the night.
Christine, Elaine and William have been visiting Drumraney for many years and join the community every year for several months – living in a house close to the Holy well of Saint Enán – a hermit who established a monastery in Drumraney around 588AD.
Over the years Linda has managed the area around their home in harmony with nature – planting additional native trees and by creating a large pond area. Christine, Elaine and William tend the garden and sow wildflowers to support butterflies, bees and other pollinators.
The exhibition was hosted by Fr Oliver Devine in the parish Church of the Immaculate Conception on October 4th, which appropriately is the feast day of St Francis of Assisi. Before the exhibition launch – at a mass to celebrate the feast day – Fr Oliver said the artists were following in the footsteps of St Francis, who found God in the beauty of nature. He spoke of how the hermit St Enán was closely connected to the wildness of the locality – and how appropriate it was now that the area was maintained and cherished by Christine, Elaine, William and Linda.
A power-point presentation in the church displayed photographs some of the work carried out at their home and garden and showed the artists preparing for the exhibition. The source of inspiration for their art was clear to see in the images shown, which were filled with amazing greenery and colourful wildflowers; it looks to be an ideal habitat for many of our butterfly species.
Peter explained to me that William, Christine and Elaine had joined the parish prayer group some years ago and from time to time they presented him with drawings and paintings. When they expressed a wish to hold an exhibition someday, Peter and Christy Grimes decided that they would organise the exhibition in Drumraney church. With Linda and Christy’s support, the three artists dedicated several months leading up to the exhibition to completing the many beautiful works which lined the walls of the church.
Last week I was invited back to the parish to accept an amazing donation of €425. Butterfly Conservation Ireland would like to express sincere gratitude to the people of Drumraney for their incredible generosity and hospitality.
We’d like to thank Peter, Christy and Linda for the considerable work that they put into setting up the exhibition and to Fr Oliver Devine for hosting the event.
Most of all we want to thank Christine, Elaine and William. It was inspiring to witness their wonderful talents and their genuine love of nature and butterflies. I look forward to visiting them again when they return to Drumraney next year.
The Drumraney artists showing their work.Habitat created at Drumraney.This flower-rich area looks ideal for butterflies.Springtime at Drumraney with hawthorn and buttercups in full bloom.
The following article has been revised and re-issued due to the volume of queries we receive concerning butterflies over-wintering in houses.
In Ireland, we have four butterfly species that over-winter in the adult form. We have a number of moths that hibernate as adults. One of these is the iconic Herald moth. A group of this species will sometimes shelter in your attic to wait for spring.
The Small Tortoiseshell butterfly has a habit of regularly entering rooms in houses to pass the winter (Occasionally, the Peacock will enter a house to over-winter, although this is unusual). The Small Tortoiseshell, a beautifully marked butterfly likes to stay close to us in late summer and will even stake out likely hibernation sites indoors especially during August and September before settling to fold its wings for winter in some obscure spot in our homes, sheds or even cars!
This well-studied butterfly has some fascinating characteristics. It has shown an ability to relocate specific sites when it has been disturbed from the site, suggesting a spatial memory; if a nettle on which a female is laying her eggs is moved, the female returns to the spot where the nettle was located, not to the site it was removed to. The butterfly is very mobile and some of ‘our’ Small Tortoiseshells may have travelled from Britain and Europe. Males establish and defend territories but if he finds a female he switches to defending the female from other males. She makes him work hard by flying away at speed to see if he can keep up. Sometimes a female (perhaps a female that has mated already) will fly into territory held by other males to enable her to escape in the ensuing confusion. A suitor may have to fight several males throughout the rest of the day. He will drive them away by engaging in a series of aerial combats, with high altitude climbs when he tries to fly above the intruder. When the intruder is expelled, the male returns to a co-operating female who usually remains perched where he left her.
Sometimes, though, she gives him the slip, giving him an anxious search as he inspects the surrounding nettle bed for her. Some females hide, and later accept defence by another male. Even a female who has cooperated with a male all day tries to lose him when she goes to roost in the nettles in the evening by dropping into the nettles and running along the ground. If the male manages to stay with her, she suddenly becomes quiet and allows mating, which lasts all night. Presumably, her demanding behaviour ensures that only the fittest males father offspring, ensuring the health of the next generation. This provides a fascinating example of selection by the female of the fittest male.
Another, related feature of the butterfly is its impressive longevity. The over-wintering generation is long-lived, and individuals can survive for 10 months. The impressive life-span allows the female Small Tortoiseshell the chance to be selective; most female butterflies accept the first male encountered; these females lack the luxury of extended life to test male powers of endurance.
However, our Small Tortoiseshells have one significant challenge when they enter our homes to see out the winter in our bedrooms, living rooms and hallways. The butterflies are very careful to select the best spots, picking excellent hiding places in curtain folds, behind mirrors and pictures, in unused chimney brests, behind dressers and, to complete the concealment, their dark cryptic coloured undersides blend nicely with their chosen surface. However, the mod con that is central heating confounds their attempts to complete their winter slumber. Heat rouses the butterfly, causing it to believe that spring, with its sunshine, flowers and nettles beckon it to fly outdoors. The confused butterfly flies around lights and windows, trying to get out.
Householders who release the butterfly into the winter are usually dooming it. The butterfly rapidly loses the ability to fly when its body temperature plummets in the cold and is picked off by birds or mammals. The other problem is starvation. The butterfly built up vital fats by gorging on nectar in our gardens and countryside before switching off for winter and long periods of unseasonable activity reduces these reserves.
What should you do if you encounter an active Small Tortoiseshell in your home?
If this happens in warm spring weather release the butterfly in the knowledge that it’s time to let it go. It is now ready to feed on the spring flowers, move in search of territories, breeding grounds and mates.
If the butterfly wakes up in winter do not release the butterfly. It should be placed in a dry, transparent container lined with a folded section of kitchen roll to absorb moisture and placed in the salad drawer in the fridge, where the temperature is around four Celsius. The butterfly will soon settle and can be kept there until warm, sunny weather arrives in March or April. Alternatively, remove the butterfly from the container when it is quiet and place in an unheated shed or room to complete its winter rest.
If the butterfly has been flying around for some time, it may need to be fed. Dissolve sugar or honey in a few millilitres of hot water, allow it to cool and use a cotton pad to absorb the sweetened solution. When cool, place the calmed butterfly (cooled in the salad drawer but not long enough to be made fully docile) on the pad, in softly-lit mild conditions. It should begin to feed. When it has finished, place in a cool place to sleep.
We advise against placing a hibernating butterfly in a very dark place such as a cupboard under the stairs. While cool and dark, it usually remains cool even when warmer temperatures return in spring. The result is that the butterfly never wakes up and will eventually die unless you find and release him/her.
Over the years I have successfully over-wintered adult Small Tortoiseshells and felt a burst of delight to watch the butterfly surge into the sunshine in spring. Interestingly, the released butterfly does not loiter. It flies strongly away, as though hyper-energised by the promise of brightness and freshness of a world renewed by the return of sunshine.
