How Ireland’s Butterflies regulate their body temperatures

Ireland’s butterfly species operate in a relatively cool climate which presents challenges to these ectotherms, cold-blooded animals whose regulation of body temperature depends on external sources, such as a cool, shaded woodland or direct sunlight or a heated surface such as a mat of dead vegetation, branch or rock.  The metabolic activity and physical movement of butterflies are highly influenced by the thermal environment. This article looks at strategies butterflies use to deal with their thermal environment.

The adult butterfly needs to fly to escape enemies, to find food, mates and breeding sites. Efficient flight is only possible when the thoracic musculature, which houses the wing muscles, reaches temperatures in the range of 35-40 Celsius. Biological functions, such as mating, egg development and egg-laying, require certain temperatures (these vary according to the species). Air temperatures in Ireland rarely reach the levels needed so how do our butterflies reach the temperatures required for efficient flight and for the metabolic activities needed to sustain life?

During our butterfly flight periods, all our butterflies deal with thermal challenges.  These can be unsuitably hot or unsuitably cool conditions. A way to raise body temperature to enable the butterfly to take flight is wing muscle vibration. This is used by a butterfly during cool weather or when it has roosted in a cool location when it is unable to use external heat sources to warm its flight muscles. Wing muscle vibration, which looks like the butterfly is shivering, allows a butterfly to create enough heat to fly to or from cover but will not allow for sustained flight. The butterfly (or moth) vibrates its wings vigorously until it has created heat by friction that enables it to fly, usually weakly and briefly, to reach a suitable location. In cool, breezy weather this strategy may not work, leaving the immobile butterfly vulnerable to predation and severe weather. Occasionally, early on spring and autumn mornings, stranded butterflies can be found resting in the open on a flower from the day before, covered in dew.

Butterflies are efficient heat seekers, frequenting warm sheltered areas receiving direct sunlight even when these sites contain fewer resources than more open sites. It will be noted that open flower-rich grassland will often have fewer butterflies than expected, while sheltered rides in woodland with fewer nectar resources can hold an abundance of butterflies and other insects. Managers of nature reserves containing open, exposed grassland should be careful to allow some scrub, a resource that enables grassland butterflies to find shelter when the weather is cool, cloudy and windy. When the sun shines, butterflies will move into more open areas. As our climate warms, scrub habitats may become vital for butterflies to escape escalating heat during the hottest times of the day or season.

Butterflies also adopt thermoregulation strategies (regulation of body temperature) that vary according to species, habitat and temperature. The wings are used to regulate temperature, both to raise and reduce the temperature.  Most of our butterflies will bask with wings held wide open when they need to increase body temperature. This is known as dorsal basking. When the thorax is coolest, the wings are held fully extended and the extreme edges of the wings are pressed against the surface, often bare soil or rock. This is known as the ‘appression’ posture, proposed in one study as potentially different from dorsal basking. This is often seen used by the Small Tortoiseshell, Peacock, Comma, Red Admiral and Painted Lady-the first three species use this technique frequently on cool, sunny days in early spring. This technique is believed to be the most efficient for increasing thoracic temperature, by trapping warm air radiating from the surface,  trapping warm air radiating from the underside of the wings and minimising the flow of cooling air around and under the thorax.

Basking with wings held off the surface in a horizontal posture is used to warm the butterfly when it is cool but slightly warmer than a butterfly applying appression.  The butterfly is absorbing heat onto the wings, but experiments with dead butterflies show that only 30% of the wing area closest to the body is used to transfer heat to the thorax.  A heating thorax causes the basking butterfly to angle its wings, forming a shallower ‘V’ as the thoracic temperature rises until the butterfly folds its wings, a posture to allow cooler air to circulate around the thorax so the insect can cool down. If it becomes too warm for this thermoregulation strategy to be efficient, the butterfly seeks shade.

Lateral basking is another thermoregulatory mechanism used by some of our butterflies. This involves basking with folded wings where the butterfly perches on a surface and angles its wing surfaces by leaning sideways onto the sun to receive the maximum solar incidence when the insect is too cool. When the butterfly is warming, it starts to correct its posture until perched upright. When the butterfly is too warm it stands head-on to the sun, raising its body off the surface by standing tall. This strategy is used particularly and rather strikingly by the Graying, and less notably by the Large Heath, Small Heath, Green and Purple Hairstreaks and the Brimstone. The Brimstone uses this especially in spring, typically by basking on dry, dead grass clumps. Using this mechanism, it can raise its body temperature to the high 30s Celsius when air temperatures are barely above 13 Celsius.

The other form of thermoregulation used is called reflectance basking. This is used by some of the whites, especially the Large White, Small White, Green-veined White and Orange-tip, although these species will occasionally use dorsal basking when they need to recover a steep loss of body heat. The butterfly perches on a surface, usually a leaf, with wings half-open. It orients its position to receive sunlight onto its wing surfaces. The white wings reflect solar radiation onto the body to increase body temperature. A dusting of dark scales on the wings near the thorax may also play a role in heating the thoracic muscles. When it is too warm, the butterfly shields body tissues from the sun by folding its wings.

A thermoregulation mechanism used by the Brown Hairstreak to avoid over-heating on its sunny, sheltered hedge habitat is orienting its closed wings towards the sun, where its shiny undersides reflect rather than absorb the light. While this appears to be lateral basking, which is used to increase body temperature, this rare butterfly mainly uses dorsal basking to warm itself. Appearances can deceive!

Let us look at how adult butterflies respond to prolonged unsuitable thermal conditions. Migration involves butterflies leaving an area that is becoming unsuitable and moving to a location where their needs are met. It enables butterflies to escape the onset of prolonged unsuitable conditions typically caused by changing temperatures. An example of this strategy is the migratory habits of the Painted Lady, which extends its range progressively from early spring onwards through summer, from North Africa, throughout Europe. This continues until the onset of cold weather when return southwards migration of the species is undertaken by the children, grandchildren and great-grandchildren of the individuals that dispersed northwards earlier in the year.

Another response by adult butterflies to prolonged unsuitable thermal conditions (in Ireland these prolonged conditions consist of low temperatures) is hibernation. This is used by the Brimstone, Small Tortoiseshell, Comma and Peacock butterflies and by several moths, such as the Red-green Carpet, The Herald and Tissue. These species remain dormant until suitable temperatures return.

The next time you are outside looking at butterflies, look at the posture it is adopting. There is nothing casual, accidental or whimsical about the way butterflies perch, they are always doing what they do for a reason. There is a lesson for us in that, but you can decide what that is!

This Peacock butterfly is using appression to heat its body. ©J.Harding.
A male Common Blue using dorsal basking. Photo J.Harding.
This dorsal basking Small Copper is angling its wings as it warms. She is feeding on a buttercup in the County Clare Burren during warm weather. Photo J.Harding.
A Dark Green Fritillary with its wings closed. This photograph was taken during very hot weather in early July 2018. On the day in question, Dark Green Fritillaries were observed entering the hazel scrub to keep cool. © J.Harding.
This female Green-veined White is using reflectance to increase her body temperature. Photo J.Harding.
This male Brimstone is using lateral basking on a warm bramble leaf to warm himself during sunny weather in early April. Photo J. Harding.
This female Brown Hairstreak has closed her wings to reflect light to reduce her body temperature.  After this photograph was taken, the butterfly adjusted its position to increase light reflectance. Photo J.Harding.


Heat Up or Chill Out?

Our temperatures are increasing. All the indications show that all our seasons are warmer, spring is arriving earlier, the growing season is lengthening. How good is this for our butterflies? Here we consider just some of the results observed and ponder potential results that may arise from the ongoing climate warming.

Weather conditions play a major role in the abundance levels of our butterfly populations, while climate change plays a deeper role, influencing abundance and distribution of species. Let us start by looking at our three regular migrants. Three migrant butterfly species are considered to recolonise Ireland each year from southern Europe or North Africa: the Clouded Yellow, Red Admiral and Painted Lady. However, nowadays the Red Admiral is commonly present here during winter, blurring the distinction between resident and visiting species. There are also indications that Clouded Yellow larvae and pupae may be overwintering in warm, sheltered spots. This has been recorded in County Wexford.

We may receive new species that are expanding in response to the warming climate. In August 2013, there was a substantial influx of the Long-tailed Blue, with around 30 individual butterflies recorded, predominantly from south and east coast counties of England. In several cases, eggs or larvae were discovered at the same locations and, subsequently, an autumn ‘home-grown’ generation of Long-tailed Blues emerged across southern England, generating sightings of at least 80 individual butterflies spread across eight counties. Although the occurrence of Long-tailed Blue in the UK in 2013 was unprecedented in abundance and distribution, the species is not able to survive our winters and so permanent colonisation is impossible at present. Amazingly, another almost identical influx of Long-tailed Blue occurred in the summer of 2015, again with substantial local breeding and the emergence of a new generation. Milder winters may allow this very successful butterfly to become established in Ireland.

Another candidate for colonisation is the Swallowtail. The Swallowtail a large and spectacular butterfly that, occurs widely in continental Europe and on many off-shore islands. Sightings of this species have increased in southern England. Two were recorded here in recent years, including one last summer. As a highly mobile butterfly, it can reach our island and may become established here if temperatures continue to increase. The species over-winters as a pupa, which may be able to survive our winters as they warm.

We may also receive the Southern Small White as a new species. Until recently, and as its name suggests, this butterfly was confined to southern and especially south-eastern Europe, but it is now spreading rapidly in a north-westerly direction, at the rate of over 100 km per year. It was first found north of the Alps in France and in Germany in 2008 and has since gradually extended its range and was first sighted in the southern Netherlands in 2015. In 2019 it was reliably recorded near Calais in France. So there is only the matter of the 22 miles of English Channel to cross before it arrives on the UK’s shores.

Of course, it may already be in the UK, just not noticed amongst its cousins.  This expanding species is likely to be Ireland’s next new butterfly.  It breeds on Candy Tuft Iberis sempervirens, commonly grown in gardens, Rock Candy Tuft Iberis saxatilis and Bladderpod Alyssoides ultriculatum, which are also garden plants. It looks very similar to the resident Small White but can be separated from it by looking at the upperside of the forewings. The black wing-tips extend as far down the leading edge or costa as it does along the outer edge or termen. In the Small White, the black wing-tip extends further down the leading edge or costa. The forewing spots are more square rather than rounded and a thin black line extends from the forewing spot (from the forewing spot closest to the wing-tip in the female which has two forewing spots) to the black wing-tip where this extends down the outer edge (termen).  If you think that you have seen this butterfly, send us a photograph!

A butterfly success that is associated with increasing warmth is the Comma, unknown as a breeding resident until it was confirmed breeding here in 2014. It is now well established in the south-east and expanding northwards and westwards. It appears to be a matter of time before it is distributed throughout Ireland. Its larva is a solitary feeder, meaning it needs warmer conditions than larvae that feed in groups that help their fellows to absorb heat, like the caterpillars of the Small Tortoiseshell and Peacock butterflies.
The Peacock butterfly, a resident for as long as records can tell us, has increased in abundance in northern parts of Ireland, where it was much scarcer before the 1990s.

Another success being associated with climate ‘amelioration’ is the Holly Blue butterfly. Until the late 1990s, this was mainly restricted to old woodland in milder coastal areas and was very rare outside these areas. Not only is it found throughout much more of Ireland, but it is also producing more generations than it did. E. S. A . Baynes (1964) considered it was single-brooded in the northern half of Ireland and double-brooded in the southern half. Today it regularly produces two generations in some counties in Northern Ireland and three in southern areas, including along the Dublin coast.

Warmer summers appear to be assisting the Marsh Fritillary butterfly, which is usually highly sedentary, especially in wet, cool summers but it will move beyond its colony in warm, dry summers, which was very evident during 2018. The species exists in many areas in a metapopulation, meaning it moves around in the landscape, repopulating sites lost during poor years. To function in this way, the species needs warm weather. Cold May and June weather can destroy colonies, so earlier springs and warmer summers may be an advantage to this endangered butterfly.

But there is always a ‘but’. Warmer drier summers and milder, wetter winters may damage some species even if these conditions benefit others. Take the example of the Small Blue, an endangered butterfly that breeds on one species plant, Kidney Vetch, that only grows in usually poor, well-drained thin and skeletal soils such as on fixed and eroding sand dunes and limestone grassland. These soils dry quickly after a few weeks of hot, sunny weather and the foodplant often desiccates, leaving it useless for breeding. Even more worrying is rising sea levels that can remove coastal dune habitats that are the main stronghold for this tiny butterfly. This is already happening along the east coast, notably at Portrane in Dublin.

More subtle changes are created by climate warming that challenges the survival of butterflies. Milder, wetter winters and earlier and warmer springs prompt plants to remain green and begin growing earlier. While this appears to be good news for some butterflies, this can prevent larvae of some butterflies from developing at an optimum rate to cut down on losses due to natural predation or may prevent some developing, starving to death on their healthy foodplants.

This paradox of heat-loving butterflies declining under a warming climate can be explained by the need of many butterfly and moth larvae for an abundance of dry, senile plant matter which is used for basking to raise their body temperature, allowing for food digestion. This is extremely important for larvae that resume feeding in early spring when air temperatures are low. This problem may be behind the crisis afflicting the Wall Brown, now in freefall across most of Ireland. It has not been seen in Northern Ireland since 2015 and is missing from most areas where it was present before the mid-1980s. I suspect this issue may be influencing the decline of the Small Heath too, for like the Wall Brown the caterpillars are daytime feeders that bask on dry, non-growing plant matter to digest their green food.

The increasingly rapid growth of the larval foodplants creates a shading effect, decreasing ground temperatures, making basking on dry stalks or bare soil impossible (if bare patches will persist for long enough under moister, warmer conditions) unless the caterpillar moves away from the plant which many larvae are reluctant to do.

The constraints on the larval micro-site temperatures may eventually be overcome if climate warming creates air temperatures that are warm enough to allow the larvae to reach the correct body temperature without the need to bask on dry, warm material. However, this is not certain either. One of the drivers of climate warming is the increased level of Carbon Dioxide. This may be affecting foodplant quality.

This is an interesting area of study, and the body of literature on this topic is increasing. At this stage, the picture emerging is that winners and losers will emerge under a warming climate scenario. A study in Germany by Habel et al. entitled Butterfly community shifts over two centuries that tracked butterflies on a dry calcareous grassland site overlooking the Danube from 1840 to 2013 found that changes in the environment associated with industrialisation and climate change are benefiting habitat generalists, especially those that use nitrogen-loving plants and damaging habitat specialists that use plants that are adapted to a low nutrient environment.

However, in Ireland and Britain, we have seen some species that were generalists or that occurred in a broad range of habitats become specialised on a smaller number of habitat types. To add to the mix, one butterfly in Britain, the Brown Argus, that was a habitat specialist has become adapted to a broader range of habitats, a development attributed to the warming climate which has allowed it to exploit foodplants that previously were unavailable because they grow in habitats that were previously to cool for it.

The story told here is a developing one. We can expect colonisation by some species, and some of our current species breeding at higher altitudes than they do now. These are likely to be habitat generalists that are following their climate envelope. What is the future of our habitat specialists, which are generally much rarer? We certainly need to protect their habitats and we need butterfly records to let us know what is happening. We don’t want to lose the plot of this tale. Send us your records, both your casual records and, if you can give the commitment, monitor the butterflies in your garden.

Here is how to provide these records, which will be published on our website and sent to a national database. Send your butterfly and moth records to us by email at

Let us know: your name/s, date of the find, species found, the life stage/s found, the numbers seen, the location the butterfly/moth was found (e.g., townland name, site name, county), and a six-figure grid reference, including the letter identifying the 100,000-metre grid square in which the location lies (see or Discovery Series maps) weather conditions and any other interesting comments you wish to provide.


John Smith (14/06/2020)

Small Blue 14, Small Heath 15 at O 254515, Portrane sand dunes, County Dublin. Sunny, light breeze, 18 Celsius.

It will be greatly appreciated if you could send in their records 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.

To count the butterflies in your garden, download our Nation Butterfly Garden Survey form below which explains how to record your garden butterflies. We will send you a report at the end of the year after you send us your survey forms.


A climate change winner, the Comma butterfly. Photo J.Harding
Small Heath butterfly, a victim of agricultural intensification and possibly a climate change casualty. Photo J.Harding
The Swallowtail may colonise Ireland if climate warming continues. It breeds on a range of plants, including Rue (garden herb), Fennell (mainly a coastal plant, also a garden herb) and Wild Carrot (widespread). Photo J. Harding

Annual Report 2020

The rain, wind and misery of January hang heavy on most people, especially on butterfly lovers, who miss the sunshine and happiness inseparable from butterflies. While we wait for better weather to renew our relationship with nature, it is nice to catch up on some reading. A good backdrop to the coming season is Butterfly Conservation Ireland’s Annual Report 2020, now available under the Report tab on this website. The hard copy of the report is free to members of Butterfly Conservation Ireland and will be posted soon. The report is available to non-members at €15.

We hope you enjoy our report and find plenty to interest you. If you have any question or inquiry don’t hesitate to contact us by email at:

or by post:

Butterfly Conservation Ireland, Butterfly House, Pagestown, Maynooth, County Kildare

We bring news of Ireland’s butterflies in our report but we also feature butterflies from faraway. This year we look at the butterflies of South Korea, in a special report brought to us by Michael Friel and Dongjun Cha. This lovely butterfly is Indian Awlking Choaspes benjaminii, related to our skipper butterflies.
Our report mainly tracks the fortunes of our native butterflies, such as the iconic Red Admiral. Like the Barn Swallow, the Red Admiral spends the summer and early autumn months here, but its winter quarters are found in warmer areas in southern Europe.

Good News

After decades of removing peat from our bogs and contributing to biodiversity loss, water and air pollution and rising CO2 emissions, Ireland is moving to biodiversity enhancement, pollution reduction and carbon sequestration. A significant step towards these objectives was taken in November when the government announced a €108m fund to add to €18m provided by Bord na Móna to rehabilitate 30,000 hectares of peatland, with more to follow.

The bog rehabilitation will involve re-wetting bogs that have been drained or cutover (a cutover bog is a bog that has been drained and has had its characteristic vegetation removed along with some of its peat).  Drains will be blocked, ditches filled in and peat profiling carried out to slow water movement on the bogs and promote the development of the bog-building sphagnum mosses which will act as carbon sinks. Among the key goals and outcomes are as follows.

Rehabilitation will support the National Policies on Climate Action and GHG mitigation by maintaining and enhancing the current condition peat storage capacity of the bog (locking the carbon into the ground). In time, it is expected that the bog will develop its carbon sink function, in part, as Sphagnumrich communities develop across the bog. It will also support Ireland’s commitments towards the Water Framework Directive, the National Biodiversity Action Plan and the National River Basin Management Plan 2018-2021. (Source: Bord na Móna Draft Rehabilitation Plan 2020).

Bord na Móna workers who previously worked in peat ‘harvesting’ will be working to restore the bogs. Walking tracks, trails and other amenities will also be constructed in certain parts of the boglands, while efforts to protect biodiversity will begin. Other peatlands will be rehabilitated outside of Bord na Móna’s landholding and it is cooperating with the National Parks and Wildlife Service to expand this operation into third-party lands over the next decade.

It is expected that work to restore peatland habitats will begin next April.

While this is very positive news, the expectation is that the natural processes involved in rehabilitating the habitats will take a long time, especially on some cutover bogs. However, Bord na Móna is confident that this can be achieved over time, but warns that “it will take some time (30-50 years) for naturally functioning peatland ecosystems to fully re-establish. ” (Source: Bord na Móna Draft Rehabilitation Plan 2020).

The prospect of bog restoration, of seeing Large Heath and Green Hairstreak butterflies and Emperor moths, of hearing the Curlew and Skylark, of smelling the sweet intoxication of heather in August, is indeed exciting.

We urge people living in the midlands to engage with the newly restored bogs, by walking on the tracks and trails provided, by photographing the habitats and wild creatures and publicising the wonderful worlds that bogs offer. Bogs need exploring carefully; their wildlife treasures do not always yield themselves to casual observation. Butterfly Conservation Ireland will be delighted to post these images on our website and Facebook page.

Butterfly Conservation Ireland has written to Bord no Móna with suggestions on how the progress of bog rehabilitation might be measured.  The presence of the endangered Large Heath butterfly is indicative of the quality of the rehabilitation undertaken because the butterfly only exists on wet bogs. Its larval host-plant, Hare’s-tail Cottongrass Eriophorum vaginatum, dies when the surface of a bog dries but the plant is frequent when the bog’s water table is at or close to the surface. This plant needs to be abundant on the bog for the Large Heath butterfly to survive. We suggested that vegetation monitoring planned by Bord na Móna assesses the density of the Hare’s-tail Cottongrass and Cross-leaved Heath Erica tetralix, the latter plant being the chief nectar source for the adult Large Heath, against the density on intact bog sites containing abundant populations of the Large Heath.

We also urged that no future use that compromises the conservation value of any rehabilitated peatland is considered. We also recommended that publicity material be generated to showcase the biodiversity benefits achieved by the rehabilitation undertaken at the various bogs. This will support Bord na Móna’s “naturally driven” philosophy and generate considerable positive publicity to highlight Ireland’s commitment to tackling biodiversity loss, pollution and climate change.

More needs to be done to protect bogs, and urgently, as many protected bogs or areas of protected bogs in private hands such as Mouds Bog, County Kildare, among many others, are still being destroyed. We need to extend climate action and biodiversity action policies to all peatlands, not just a few.

However, we commend the Irish government on the steps taken to cease peat exploitation on Bord na Móna bogs. A lot done, but more to do.

Update on December 14th post

In January 2021 Bord na Móna announced that it has ended turf cutting throughout its estate.

Making the announcement, Bord na Móna Chief Executive Tom Donnellan said: “The Brown to Green strategy has involved the transformation of Bord na Móna from a traditional peat business into a climate solutions company. The progress made over the past two years means we are now fully focused on renewable energy generation, recycling and the development of other low carbon enterprises. While there are many advantages to the changes we have made, the key benefits include the high value, sustainable employment we are providing and the significant support we are delivering to Ireland’s objective, to become carbon neutral by 2050.

As we have put our new climate-focused business in place, we have also completely stopped a number of high carbon operations and transitioned others to a more sustainable model. During this period, peat harvesting has already been wound down and stopped. The company’s last full peat harvest took place in 2018, followed by a partial harvest in 2019 and a full suspension of harvesting operations last year. The company has today decided to make this suspension permanent and cease any remaining harvesting preparations, including planning and substitute consent applications. Today marks the formal end to the company’s association with peat harvesting, as we move on to tackle the critical challenges concerning climate change, energy supply, biodiversity and the circular economy.”

Butterfly Conservation Ireland warmly welcomes this development. We want to see the end to all peat cutting on Bord na Móna land, including cutting by operators with contracts with Bord na Móna to cut peat on Bord na Móna land.

Some bog beauties follow…

Common Darter. Photo J.Harding
Red Admiral Photo J.Harding
Green Hairstreak Photo J.Harding
Eyed Hawk-moth.©J.Harding.
Marsh Fritillary. Photo J. Harding.
Marsh Fritillary Photo J.Harding
Emperor Moth  Photo J. Harding
Some rehabilitated areas will contain flooded areas that will provide habitat for wetland plants, birds and aquatic animal groups such as amphibians and dragonflies. Photo J. Harding


Where does our environment stand now?

It is late November 2020 as we near the end of the second decade of the second millennium. It is time to ‘take stock.’ How are our precious habitats and wildlife populations coping with our behaviour?

Let’s see what Ireland’s Environmental Protection Agency (EPA) has to report on the state of Ireland’s precious habitats

Listening to the EPA Director General Laura Burke on RTE Radio 1’s Morning Ireland on Wednesday 25th November, we are performing poorly.

Some headline statistics underscore the deterioration in the quality of our surroundings. We have 20 pristine rivers today compared with over 500 in the 1980s. Raw sewage is being discharged to water from 35 towns and villages. 90% of Ireland’s energy is still being generated from fossil fuels; air quality in some urban areas does not meet World Health Organization standards.  85% of Ireland’s EU-listed habitats are in an unfavourable condition.

These habitats are legally protected, but this is rarely enforced. Just look at Mouds Bog, County Kildare (among many other ‘protected’ bogs), being ravaged by illegal drainage and peat cutting while the body charged with protecting these habitats, the National Parks and Wildlife Service (NPWS), stands idly by, watching it all happen. And doing absolutely nothing to stop this, other than producing bland letters describing various (meaningless) policy initiatives to protect rapidly vanishing peatlands.

Dealing with habitat protection is not a resource issue for the NPWS, it is a problem of identity, leadership and culture. As for identity,  the NPWS is not an agency or even a single body – lately, it sits within the heritage division of the Department of Housing, Local Government and Heritage, alongside the National Monuments Service and Built Heritage, Architectural Policy and Strategic Infrastructure. As for leadership, there is no head of the NPWS as such; responsibility ultimately lies with the minister of the day. The culture within the organisation means that it is ill-suited to its task. I once made 11 phone calls to a range of phone numbers to report suspected damage to a protected site before I received an answer to the call. When the appropriate person made contact, several days later,  I was told that their phone was out of range. This I knew to be untrue, and I made this known. An embarrassed silence followed.

The officer did make a site visit and all was well, thankfully, but the issue was not processed in a timely manner. Non-governmental organisations like Butterfly Conservation Ireland should not need to insist that our environmental laws are upheld. The NPWS exists to fulfil this function, among others.

Sticking with the NPWS function to defend habitats that have legal protection, there are some excellent NPWS staff absolutely committed to their roles.  These men and women do excellent work, using their powers to protect our environment. They get little or no encouragement from within the organisation, and some may feel isolated and vulnerable. The sense is that there is little chance of promotion for zealous conservation officers. This conveys a dysfunctional culture and leadership failure-in such cases, one is relying on people of honour to do their jobs properly. Luckily, NPWS has such caring, brave staff.

For the sake of the tawdry remnants of our bogs, let us hope that NPWS continues to have their service. But more of these dedicated people, and overall reform and serious will, is needed.

Ireland has a reputation for having a clean environment. The new EPA report shows that this is undeserved. The state signs up to various environmental commitments and then largely ignores delivering on them. Thus, the state agreed to the European Union Habitats’ Directive as a European Union member state and designated Special Areas of Conservation and Special Protection Areas. Some features (known as qualifying interests)  used to identify Special Areas of Conservation, such as the presence of particular species, now no longer exist on a number of the designated sites, due to site deterioration arising from illegal damage and or bad management.

Such deterioration may lead to call for the site to be delisted as a protected site-it is hard to see how some raised bogs can remain on the protected list after the damage done to them. A cynic might say that this is how the state hopes to evade its responsibilities to protect these delicate sites.

If that is the plan, it is working.

Raised bogs are on the brink of extinction in Ireland, thanks to a refusal to protect them.
The Large Heath butterfly lives nowhere else except on wet bogs. Its future in Ireland lies in our hands. Photo J. Harding.



What is flying in November

The clocks have moved back an hour, sounding the death knell for Irish summertime. In truth, the summer left us some time ago. Time: the indefinite continued progress of existence and events in the past, present, and future regarded as a whole.

One of time’s markers is the appearance of the species of butterfly and moth because each species has its slot or slots in the year. For those on intimate terms with our species flight times, we can mark the seasons according to the emergence of butterflies and moths. Sometimes we are surprised. Every so often, we see a species when we shouldn’t.

In February, statistically our coldest month of the year, we don’t expect to see Brimstone butterflies. On 25th February 2019, Pat Wyse recorded nine Brimstone butterflies in Lullymore and Lullybeg, in County Kildare. We had an unusually balmy week and Brimstones woke early. But they looked out of place. Their breeding plants were not ready. Luckily, early dandelions provided nectar. Other records of early butterfly sightings flooded in.

The early opening to the Brimstone flight season did not do the butterfly any harm judging from the large generation that flew later in the year.

However, the Brimstone can appear at odd times because it exists as an adult butterfly for most of the year. In fact, it can be seen in any month, although it is abundant mainly in April/May and August. But to see it in February is very unusual and requires unusually warm, sunny weather.

The year 2020 had early emergence dates for spring butterflies but afterwards the weather dipped, giving us more typical flight times for summer and autumn flyers. We are having a mild autumn and there are still butterflies and moths flying.

The Comma is still on the wing and is feeding on ivy blooms and late flowers in gardens. At this time of year, it will spend long periods basking on warm, dry surfaces, such as bare earth, tracks, tree trunks and garden decking. Stephen Lawlor has sent in the lovely photo of a Comma basking in his garden. It looks especially beautiful in autumn sunlight-when seen in the flesh, it has an incredible glow, a stirring warmth to excite the eye.

The odd Small Tortoiseshell is being seen. George McDermott has seen the species in Donegal, taking nectar on late-flowering  Perennial Wallflower  ‘Erysimum Bowles Mauve’. A few Red Admirals are still out there; indeed, they are still breeding in Howth, County Dublin, where Frank Smyth keeps a close watch on their development over the colder months of the year.

Last night I saw my first December moth of this season, a male twitching his feather antennae under an outdoor light. Usually, I see this moth later, at the end of November and during December. Check under outdoor lights during mild nights for this species.

The lovely Red-green Carpet is flying now, but you really need a light trap to attract this species. The moth mates in autumn but males die, with the mated females entering hibernation. At this stage, the moths feed on ivy flowers. When the females wake in spring, they feed on sallow catkins.  They will lay their eggs on birch, lime, oaks and other trees and shrubs.

The well-named November moth is flying too-a cryptic grey moth flecked with black. Yellow-line Quakers, also requiring light traps to be found, also occur during November; again ivy flowers are used for feeding. These two species leave their eggs behind before the adults die. The eggs of both species are laid on native trees such as oak, birch, hazel, hawthorn and others.

However, these species represent a late flowering. Soon, apart from a small number of winter specialists, we must wait until spring to see the glow of butterfly wings in flight.

Start getting your garden ready for spring!

Comma basking. Photo Stephen Lawlor.
Red-green Carpet. Photo J.Harding.
Small Tortoiseshells can fly well into November. Photo J.Harding.
November moth. Photo J.Harding.
Red Admirals will breed even in winter in mild coastal areas. Photo J.Harding.
December moth. Photo J.Harding.
Small Heath caterpillar. Photo J.Harding. The Small Heath caterpillar is very difficult to find in the wild. The caterpillar will feed during the day throughout the winter during mild, sunny weather. The caterpillar in this photograph is c.8mm in length and is in the fourth of five instars.



What are you looking at?

(Note: this article has a glossary for the terms in bold.)

In the pre-COVID July of 2019, I spent a happy half-hour observing a  ‘Common Blue Polyommatus icarus’ in a disused limestone quarry at Hondoq, Gozo. The early afternoon of July 19th 2019 was sweltering, with temperatures well into the 30s Celsius.

The lone freshly emerged Common Blue was staking out his territory, settling on a range of perch posts, all with a commanding view over the terrain. Luckily for me, he was not very active or shy, so I was able to get to within 20 mm, which enabled me to take some photographs.  Even better, he opened his wings so I got a glimpse of his beautiful, gleaming blue uppersides-something this species will not often allow in in extreme heat when wings are usually kept closed to avoid overheating.

When I checked the photographs later on my laptop, I was surprised to see some differences with the Common Blue I am used to seeing. It was smaller but that is not too surprising because smaller adult specimens often arise when their larval foodplants are hit by drought. The blue was deeper than usual but the depth of colour of a blue butterfly often depends on light intensity and viewing angle so this is not particularly decisive.

However, the specimen had small but well-defined black spots near the edge of the upperside of the hindwing and black dusting along the outer edge of the forewing upperside, extending further inwards than usual; the typical male has a black pencil outline along the length of the outer edge and along part of the upper costal area of the forewing upperside.

After further checking, I realised that I was probably not looking at the Common Blue Polyommatus icarus, but at a species identified in 2008 by the Russian Academy of Science, Polyommatus celina. This study revised the status of  Polyommatus icarus form celina to Polyommatus celina. This revision means that the butterfly is no longer regarded as a form of the Common Blue (it was formerly regarded as the celina form of the Common Blue) but as a new species.

The study found a difference of greater than 6% in the mitochondrial DNA between the Common Blue and Polyommatus celina, now referred to as the Southern Common Blue.  This is a high degree of genetic divergence. The Russian study also found morphological differences (observable physical differences, such as the darkening on the upperside of the male forewing).

Southern Common Blue Polyommatus © J.Harding.
Southern Common Blue Polommatus celina underside © J.Harding.
Southern Common Blue female underside © J Harding.

The recently identified Southern Common Blue uses Common Bird’s-foot-trefoil as a foodplant for its caterpillar, as does the Common Blue. On the Iberian peninsula at least, the two species occur in the same areas and mate. Introgression has been shown to occur in the Iberian peninsula.  From personal observation, it appears both species may occur on Gozo too, but a 2011 study by Dinca et al. states that “The two species appear to completely exclude each other on islands”.

Perhaps the reason males were chosen for a comparison of wing characteristics is that these are far more consistent in male blues than in females so that any difference stands out. The Common Blue females in Ireland, for example, show remarkable variation. Some of the variations are shown here.

These two studies highlight the vital importance of conservation, which includes protecting not simply species but genetic diversity within species.  Under the Wildlife Act 1976 Section 11 as amended by the Wildlife Amendment Act 2000 protection of biological diversity within species as well as between species is a function of the Minister.  The amendment arose from Ireland’s ratification of the UN Convention on Biological Diversity in 1996 – a landmark convention for the conservation of the diversity of natural life on earth. Just one key issue here is that similar-looking butterflies have been found to be separate species. This can have important implications for conservation, especially when a species believed to be widely distributed and not in need of protection measures proves to be a separate and endangered butterfly.  It is vital that genetic and morphological analysis continues to examine butterflies so that conservation needs can be clarified.

This analysis was responsible for separating two cryptic species that occur in Ireland, the Wood White, which has been shown to be confined to western limestone areas and the Cryptic Wood White, a much more widespread butterfly. There may be more to discover.

Look at the following photographs of the Common Blue found in Ireland. While the males appear similar in colouring, the butterfly varies in size, although this is a feature common to most species.  The apex of the forewing often looks more pointed than in specimens found in England. However, females are highly variable. This variation occurs within populations, between seasons, years, localities and regions. Generally, females found in the north and west are ‘bluer’ than those found in the east and south, which are ‘browner’ on their uppersides.

These variations have been attributed to the Common Blue’s ecological adaptability.  The extent of blue colouring in the female may correlate positively with cooler and or damper conditions during larval and pupal development. This would explain the prevalence of ‘blue’ females in north and west Ireland and NW Scotland. In these areas, the Common Blue is regarded as a distinct subspecies called mariscolore. This ranking is based on morphological features, the extensive blue on the females and the brighter blue of the males, the male’s larger size and more pointed forewing. Furthermore, this population might be single-brooded-it certainly is in Scotland and remains single-brooded even when reared in the south of England. This suggests a genetic difference, supporting the idea that NW Scottish Common Blue is a subspecies (or even a separate species?)

My records and breeding experiments and the records of many recorders do not support the idea that subspecies mariscolore is single-brooded in  North-west Ireland.  This does not mean that the Common Blue found in the west and north is genetically identical to populations found elsewhere in Ireland.  The picture is very confused, however. Females referrable as subspecies mariscolore and females referable as the typical (nominate form) mainly ‘brown’ form are not infrequently found together, both in the west of Ireland and midlands. Subspecies are usually regarded as occupying a distinct geographical region, separate from other populations of the same species and having constant and clearly different characteristics. These populations are not meant to overlap with other subspecies or with the typical form of the species. However, butterflies do not always conform to definitions!

In the absence of genetic analysis, we need to keep open the possibility that we have additional blue subspecies or species, perhaps endemic, on our island.  If a reason to protect genetic diversity within species is sought, surely this is one such reason, among others.

Enjoy the beauty below…

Common Blue male Lullymore County Kildare © J. Harding
Common Blue female, Lullymore, County Kildare. © J. Harding.
Common Blue female, Lullymore, County Kildare © J. Harding.
Common Blue, female, County Meath © J.Harding.
Common Blue female, County Clare © J. Harding.


Costal: the front/leading edge of the forewing/hindwing.

Endemic: a species found only in a limited geographical area (The tree Irish Whitebeam Sorbus hibernica occurs only in Ireland).

Form:  any classification below the level of a subspecies that refers to ecological, seasonal or sexually dimorphic/polymorphic forms.

An ecological form is a form that develops in response to conditions in the butterfly’s environment. Thus, a darker colouring is often associated with a butterfly population that lives in a cooler, damper climate as an adaptation that enables a basking butterfly to absorb heat from the sun.

seasonal form is a form that is associated with a multi-brooded species. Thus, the Large, Small and Green-veined Whites occur in two-three broods in one year, with progressive darkening of the dark markings over the season.

Sexually dimorphic forms are differences in wing markings (Large White) and colouring (Orange-tip) between the sexes.

Introgression: in genetics, this is the movement of a gene from one species into the gene pool of another by the repeated backcrossing of an interspecific hybrid with one of its parent species. Purposeful introgression is a long-term process; it may take many hybrid generations before the backcrossing occurs. Introgression differs from simple hybridisation. Over time, offspring with a genetic identity close to that of one of the two species will be achieved.

Mitochondrial DNA: DNA found in a unit of the cell outside the nucleus. The mitochondria produce energy for the cell.

Morphological: referring to the study of the appearance, size and shape.

Subspecies: A population occupying a distinct geographical region, separate from other populations of the same species, and having constant and clearly different characters. Such populations have the potential to interbreed and therefore cannot overlap.




Responsible gardening protects wildlife

Gardening is a great activity that builds health, pride in one’s home and offers insights into the world of nature. Unfortunately, some gardening has created massive biodiversity challenges which could easily have been avoided. Here we look at a few plants you should definitely avoid.

Montbretia Crocosmia x crocosmiiflora is a hybrid of a species originating from South America. Undeniably attractive, it is, unfortunately, extremely invasive. It escapes from gardens and is sometimes deliberately planted to beautify hedgebanks adjoining gardens.

The plant is not used for breeding by our butterflies or moths. Even worse, it grows in dense clumps that completely exclude native plants. It is becoming established in many places around our island, including in the County Clare Burren,  in west Kerry, in Donegal, Kildare and many other areas, even in areas with low human population density. It is damaging many protected habitats, including Special Areas of Conservation on state-owned land. It spreads by the division of underground corms.

Recently I pulled up metre high clumps from a roadside in the Burren and observed that no other plant was present where the Montbretia was grown. It is displacing all flowering plants and grasses. I particularly noted that the highly attractive Tufted Vetch, used by the rare Wood White for breeding, was also absent from areas where Montbretia was established.

The Montbretia along this stretch of roadside in south-west Donegal replaced violets, Harebells, Common Knapweed and vetches. Photo J.Harding.

This threat must be tackled, by all of us. Avoid planting it in your garden-there are more attractive, butterfly-friendly native plants such as Devil’s-bit Scabious that you can use instead.  If you have a weakness for it, never allow it to escape into the countryside.

If you see it in the hedges near your home and want to protect the environment, pull the clumps up-they are easy to pull up and the corms come with the rest of the plant. You must not put the material in the compost bin. It must go to landfill.  If you are left with a large area of bare soil after the plants are removed, sow native seed from nearby by simply tossing it on the soil surface-do not bury the seed.

Another non-native that damages native hedges is Fuchsia magellanica ‘Riccartonii’. This originates from Chile and Argentina and is probably the hardiest of all the Fuchsia here. This plant is out of control in parts of the west of Ireland where it overwhelms native shrubs. It appears to be very difficult to remove without digging it up or treating the freshly cut main stem with glyphosate.

Another invasive that some gardeners love is Red Valerian. Again it is pretty and it is a good source of nectar. But it is highly invasive when it becomes established on free-draining soils and rocky areas such as limestone pavement where it can become dominant very quickly.  It is currently established at Ailwee Mountain in County Clare where it is out-competing Common Bird’s-foot-trefoil, an important breeding plant for some moths and butterflies. It has taken hold at Bull Island, County Dublin, on the dunes which are especially noted for their orchids.

This plant can be pulled up but the roots can be hard to remove all the roots when it is established on limestone pavement.

Our wildlife has enough challenges to deal with without needlessly adding more problems in the form of invasive inedible non-native plants that displace important foodplants. Native plants are here for good reasons. They have existed alongside a suite of other plants and animals and formed important biological relationships which must not be disrupted.

If you want to plant flowers and shrubs in your garden, take a look at the species that occur naturally in your area and use these. The local native plants will add great wildlife value to your garden and you can make a real contribution to nature, both directly in your garden and indirectly in the wider area.  You will also be caring for nature by not growing invasive non-native plants.

Our native trees and shrubs are beautiful and some are available in good garden centres. However, just because a garden centre sells plants does not mean it is a good idea to buy them. In our view, garden centres should not sell invasive species. While it is not illegal to plant such plants in your garden, it is illegal to introduce exotic (non-native) plants into the wild (Section 52 of the Wildlife Act 1976 as amended by Section 56 subsection 7 of the Wildlife Amendment Act 2000).

For nature, think native. Non-native plants can ruin habitats. This is happening worldwide as well as in Ireland.  If we allow non-native plants to overwhelm our countryside, sights like this may become consigned to the past.

A Brimstone butterfly feeding on a lovely native flower, Devil’s-bit Scabious. Photo J.Harding.

Free Offer

Devil’s-bit Scabious is a magnificent native perennial and grows happily in most garden soils.  It flowers from August to October and delivers nectar to butterflies, moths, bees, etc. Its seed is eaten by Goldfinches and Lesser Redpolls.  If you would like us to send you some Devil’s-bit Scabious seed, send a stamped, self-addressed envelop to Butterfly Conservation Ireland, Pagestown, Maynooth, Co. Kildare. Offer available while stocks last.

Event Reports

Site Management at Fahee North, County Clare

COVID-19 has severely curtailed events this year but we did have two events on September 5th and September 6th in the Burren, County Clare.

On Saturday, September 5th Butterfly Conservation Ireland and Burrenbeo Trust teamed up to cut scrub on the wonderful habitat just north of the Burren Perfumery near the site of St Fachtnan’s Holy Well.

Owing to various weather and COVID-related cancellations, we have not been able to get on the site to manage it. In short, there was and still is much to do!

Ten of us got stuck into the scrub that has encroached onto the highly species-rich grassland. The site contains a very large range of flora, including rare plants such as Hairy Violet.  Mountain Avens, Spring Gentian, Goldenrod, Bloody Cranesbill, Devil’s-bit Scabious, Meadow Thistle, Lesser Meadow-rue, eye-bright, Common Cow-wheat, Common Dog-violet and several species of grass occur on the site.

The main threats are presented by the spreading of Common Hazel and Common Blackthorn, which must be kept under control if the rich flora and associated butterflies are to be conserved.

Smaller, more isolated hazel plants were uprooted while established scrub was cut. This will have an important impact as it reduces shade and uncovers flora that was hidden and unavailable for breeding by butterflies.

We were able to see some Marsh Fritillary caterpillars on a well-developed Devil’s-bit Scabious plant and noted how the plant was sheltered by the shape of the adjoining ground and unshaded, making it an ideal site for the larval nest. These are among the conditions our work is designed to maintain.

After a solid morning’s work, we rested for lunch and chat, while we looked at our work and the lovely landscape all around us. We returned and the group I was with finished clearing ‘our’ patch of scrub.

We finished at 4 pm, tired but happy, knowing we were back outdoors, together, at last! The site will now be grazed to improve the sward so by the time we are back in February we will see a great improvement.

A big thanks to Anne Mullen and Kate Lavender for all the organisation of the event and all the conservation volunteers who helped.

St Fachtnan’s Holy Well is near the northern edge of the site at Fahee North, County Clare.
This Coxcomb Prominent moth caterpillar was found on the site.
Mountain Avens, a classic Burren flower blooms on the site.
Goldenrod, a lovely flower found on the Burren limestone.
This photograph shows a part of the site rich in Devil’s-bit Scabious, an important source of food for autumn butterflies and the foodplant of the caterpillars of the Marsh Fritillary butterfly.

Walk in the Burren National Park,  Knockaunroe, County Clare

On Sunday 6th September we had a fine, sunny afternoon for our walk in the Burren National Park. We had 16 people for our event, reduced to incorporate social distancing.

The partly reclaimed area has developed into a beautiful mix of scrub and flower-rich limestone grassland containing habitats of the highest quality for a large suite of butterflies and moths.

A wet summer did not help us to see many butterflies but we obtained good views of the important areas and we did see some species, especially Speckled Wood butterflies. The males could be observed flying to and fro patrolling their scrub edge territories while females kept a low profile by flying low to the ground, fluttering around grass blades close to scrub in their search for suitable places to lay their eggs.

Some late Meadow Browns and some Small Tortoiseshells were seen along with a white butterfly, either a Small White or Green-veined White.

Dragonflies, mainly Brown Hawker and Common Darter were seen flying over the grassland and along the scrub, picking off small insects in flight. In truth, numbers of insects appear well done on previous Septembers, but the pleasant, gentle autumn sunshine and excellent conversation made for a memorable day.

A special thanks to Pranjali for organising the event.

The Burren National Park at Knockaunroe, County Clare.

Small Tortoiseshell Butterfly of the Year 2020

For some butterflies a year gets it just right. A lovely, prolonged almost rainless spring with warm sunshine on most days in April and May followed a wet February. These conditions helped the Small Tortoiseshell butterfly to launch its year.

When it wakes from its hibernation in spring, the Small Tortoiseshell needs warm weather to fly. The butterfly needs to feed, find mates and the females look for nectar to develop their eggs and then seek suitable breeding sites. The larval foodplant, the Stinging Nettle, is not well developed in March and early April so the females must continue to feed and develop their eggs. When she is ready to start laying her eggs, it is vital that suitable nettles exist.  By mid-April this year, the nettles reached a suitable size. There were excellent weather conditions for egg-laying. The sunshine helped females that had laid their first egg batch to take nectar to develop further egg batches and disperse to reach new breeding sites. The eggs, larvae and early pupae developed quickly in the warm sunshine during May, with the first new-generation adults observed by June 1st.

After some very hot weather during the first week in June, the rest of the month saw above-average rainfall and temperatures near the average for June. This helped because a continuation of the drought conditions that developed over the spring months would have reduced the suitability of the nettles. These were now refreshed, and grew strongly, making for excellent breeding conditions for the vast number of Small Tortoiseshells that emerged during June and July.  Most of these butterflies stayed close to nettles and bred. The off-spring of these mid-summer breeders are appearing now, in very large numbers in some eastern areas.

Unlike their parents in mid-summer and grandparents in spring, this generation, the second born in 2020, will, in the vast majority of cases, not breed this year. It is their need to feed heavily in preparation for a long overwintering period that brings them to our gardens and to our attention.  Seeking nectar, the butterfly turns up in warm, flower-rich,  sheltered areas near suitable overwintering sites where they settle to feed. Their focus on feeding without expending energy makes them very easy to approach with some so docile that they can be touched without taking flight.

Small Tortoiseshell butterflies busy feeding in preparation for overwintering are quite tame. This behaviour is diagnostic of a delayed breeder. Photo J.Harding.

These make for lovely viewing and there have been spectacular numbers, with hundreds seen at Pollardstown Fen, County Kildare on August 30th. On that date, I saw around 400 on the bog at Lullymore and Lullybeg in County Kildare and 22-27 in my garden in County Meath each day for most days over the past two weeks (to September 1st). One indication of high numbers for anyone who does not seek the butterfly in its prime feeding stations is that it can be seen in low numbers flying across roads, fields, parks and other areas in its search for food.

The weather conditions we are seeing now with mild air and good sunshine is of great benefit to this overwintering generation because they have the conditions needed to move to good sites, feed and seek places to see out the colder months.

We urge you to enjoy seeing the butterfly because its current high abundance is quite short-lived. A butterfly that needs to survive for several months in the adult stage cannot expose itself for too long. The habit of feeding in large groups makes it an easy target for insectivorous birds, especially members of the tit family, wrens and robins. The Small Tortoiseshell is slowing down at this stage (its increasing weight and falling temperatures make it heavier and slower), making it easier to approach and catch. In short, it spends only a few weeks feeding before hibernating until next spring.

During September numbers fall, although newly emerged individuals that arise from eggs laid later in summer, probably by late-emerging or older females will appear into October. Some of these October butterflies may represent a small third generation, meaning that their parents that emerged during August bred rather than attempting to overwinter.

Up to three generations of the Small Tortoiseshell may overwinter in some years. Indeed, some of the first generation of Small Tortoiseshells that arose from eggs laid last spring do not breed in June and July but enter hibernation. These are probably few in number in most parts of Ireland, but this overwintering strategy of some first-generation adults is implied from observations made of adult behaviour in Counties Dublin, Meath and Donegal. Therefore, there may be three generations of the butterfly in hibernation over the winter.

Regardless of which generation the butterfly is from, it enters our attics, sheds, outbuildings, homes, woods, dense scrub, caves and other sites that will shelter it until spring.

When they awake in good weather, usually later in March we are looking at butterflies that range in age from five to eight months. We are also looking at siblings, aunts, uncles and cousins on the wing at the same time. This does not necessarily mean that all of these individuals are breeding with each other because the Small Tortoiseshell is a mobile butterfly that will travel to seek mates and breeding sites. However, in Britain, it has been found that the butterfly does not travel large distances across the country because Small Tortoiseshells from different regions show a different response to day-length. Thus, larvae that were taken from Scottish populations always produced adults that delayed breeding until spring, irrespective of the amount of daylight they received.  In the south of England, the butterfly has shown the ability to produce three generations.

There is much more to learn even about common butterflies like the Small Tortoiseshell.  A study in the UK found that much of the variations in the Small Tortoiseshell’s phenology (the study looked at emergence peaks) are unrelated to temperature or northing (latitude) (Hodgson et al. 2011).  Whether a similar study carried out here would show a similar result is unknown. However, the UK study did not take account of various effects of winter minima, summer maxima, rainfall, and cloudiness. That is unfortunate;  for example, the issue of cloudiness is relevant because the species is expected to respond to features such as photo-period (amount of light received, day-length).

It appears that the butterfly is faring better in Ireland than in Britain. Here the population is regarded as stable (‘2019, the year of the Painted Lady’, The Irish Butterfly Monitoring Scheme Newsletter, Issue 13). ) while in the UK it has shown a significant major decrease in abundance of -73% from 1976-2014 (Fox et al. (2015). The State of the UK’s Butterflies 2015. Butterfly Conservation and the Centre for Ecology & Hydrology, Wareham, Dorset.). It should, however, be noted that the Irish abundance study covered a shorter time (2008-2019) than the UK study. We can add 2020 as another year when the Small Tortoiseshell abounded in Ireland. Long may it continue to flourish.

Small Tortoiseshell, in our gardens now. Remember to record it for our National Garden Butterfly Survey. Photo J.Harding