The following article by Jesmond Harding appeared in The Irish Times on February 3rd 2018. The brief was to say what February means for seekers of butterflies in 150 words.
February is a winter month, and the year’s coldest, says Met Éireann. For butterfly-lovers, February continues the butterfly famine. Butterflies that over-winter as adults remain concealed in woodland, muted underwings blending with greys and browns of tree trunks or mimicking holly, bramble and ivy leaves, in the case of the Brimstone butterfly.
Spring is coming even if it seems a distant hope. The poet Edward Thomas suggested that, in February, spring must be dreamed up. To ideate spring the butterfly-lover seeks the white golf-ball eggs of the Brown Hairstreak butterfly on dark leafless Common Blackthorn stems and nests of spiky hedgehog-like caterpillars of the Marsh Fritillary, huddling together in lucid February sun.
Occasionally, a warm day rouses a Peacock, Small Tortoiseshell, Comma or Brimstone butterfly. These bask on walls, tree trunks and tufts of dry grass litter, but soon return to their winter abodes. They’re not out of the woods yet.
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.
One of our butterflies has a habit of entering rooms in houses to pass the winter. 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 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 butterflies are likely to fly here 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, with the male often having 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 his 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 which 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 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 an 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 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 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.
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.
It is December 8th and the Met Office is forecasting a bitterly cold month ahead. How will this impact on our butterflies? Butterflies are regarded as creatures of the light, lovers of sunshine and warmth, vulnerable to the onslaught of bitter winters. We rarely have cold winters and with climate warming we may get even fewer, so how will this change the fortunes of our butterfly and moth populations? The connection between extreme winter warmth and butterfly population levels was researched by East Anglia University, Butterfly Conservation UK and the Centre for Ecology and Hydrology (McDermott Long, O., Warren, R., Price, J., Brereton, T. M., Botham, M. S. and Franco, A. M. A. (2017), Sensitivity of UK butterflies to local climatic extremes: which life stages are most at risk?. J Anim Ecol, 86: 108–116. doi:10.1111/1365-2656.12594).
It was already known that butterflies do better in warmer summers but, perhaps unexpectedly, the new research which looked at the impact of extreme climate events on the population of butterflies in the UK from 1976-2012 revealed that extreme mild winters have a negative effect on the populations of just over half of the 41 species studied. It is interesting to observe that these negative effects occurred regardless of whether the species affected are widespread species or habitat specialists. All four of our butterflies that over-winter in the adult form, the Comma, Small Tortoiseshell, Peacock and Brimstone showed a negative impact of extreme winter warmth (disruption of over-wintering in these species may result in losses from predation and decline in fat reserves). Species that showed a similar result and the stage in which these over-winter are the Purple Hairstreak (egg), Dingy Skipper and Dark Green Fritillary (larva) and Orange-tip (pupa).
Only two of the species studied showed that there is a positive effect of warm winters; these were Wall Brown and Holly Blue. Extremely cold winter days were associated with significant population increases in the Large White (over-winters as a pupa) and Ringlet (over-winters as a larva).
Overall, the study found that cold spells in winter were beneficial or neutral in the impacts on population size while warm spells in winter were generally harmful. An additional and unexpected finding is that the pupa of butterflies that have one brood per year show sensitivity to extreme precipitation.
Another recent study, from Stockholm University also using data from the UK (Stålhandske, S., Gotthard, K. and Leimar, O. (2017), Winter chilling speeds spring development of temperate butterflies. J Anim Ecol, 86: 718–729. doi:10.1111/1365-2656.12673) found that some butterflies that over-winter in the pupal state emerge earlier in the year during a warm spring but not after a warm winter. Three species of the five species studied, Green-veined White, Orange-tip and Green Hairstreak flew earlier in spring after a cold winter. The study found that warm winters delay emergence. This earlier spring emergence might be due to the insect being programmed to emerge from the pupa after experiencing a prolonged period of cold followed by a period of warm conditions; this temperature change process is used to obtain specimens out of season in captivity. This involves placing a pupa in a refrigerator for some weeks and then keeping it at room temperature which causes early emergence, mimicking the effects of the passing of winter and onset of spring.
With climate change expected to continue, what are the main implications for our species? The findings are mixed. Warmer summer weather, as long as drought does not occur, may well help populations to increase and spread. Extreme climate events, such as extreme warmth and extreme rainfall in winter may cause declines. High quality habitats may have the ability to buffer extremes, so it is vital that habitats are managed as carefully as possible to provide the best chance of survival for our butterflies and moths.
When you see the snow and ice over the coming days, please take care, but remember that our butterflies are well-adapted to these conditions which may be necessary for their long-term survival. Snow and butterflies are compatible!
Weather-reliant activities are hard to plan in Ireland and Saturday 11th November, promised dry two days before, slowly descended into a wearying drizzle.
Undeterred, the Butterfly Conservation Ireland work party knuckled down to do battle with regenerating scrub close to where scrub was tackled last year. Our youngest workers, Annie and Conor helped by enthusiastically tucking into the work of uprooting birch saplings and cutting young re-growth on willow and birch. Taller material was felled and the resulting cuttings piled neatly to rot down naturally. A great impression was made on the encroaching scrub with these areas now much more open to light, creating breeding sites for grassland butterflies like the Marsh Fritillary, Dingy Skipper and Common Blue.
The process of halting and reversing natural succession (the process of change in biological communities over time) at Lullybeg is needed to ensure that the climax vegetation in much of the managed area of the reserve remains species-rich grassland. Left to develop its climax vegetation naturally, the site will become woodland dominated by birch and willow and its grassland butterflies would be lost. The grassland butterflies and moths specialise on herbs growing in a grassy sward that is open and unshaded. The shading of grassland reduces the light and temperature, making these areas unsuitable for breeding for most of the reserve’s butterflies. Some butterflies, like the Brimstone, breed in open scrub while the Silver-washed Fritillary likes open, sunlit woodland. There are areas of the reserve where the needs of these species are accommodated. In this way, a habitat mosaic is provided, with a range of habitats scattered throughout the site which are maintained by active conservation management.
Butterfly Conservation Ireland thanks everyone who made a vital contribution to conserving the butterflies moths and other insects on this rich site. We will have another conservation day in February, when we hope for bright spring sunshine!
The Brown Hairstreak is one of our most elusive yet most conspicuous butterflies. The adult is rarely seen but the egg is easily found. This paradox may be part of the butterfly’s appeal. Among butterfly lovers in the UK the Brown Hairstreak has a cult status, evidenced by having its own blog (http://betulae.blogspot.ie/). It is an attractive butterfly, the female especially delightful with a warm golden underside with a patch of the same striking hue on the upper-side of the fore-wings. Aside from the golden patch the upper-sides are dark brown. Males look similar, but the underside gold is paler and the fore-wing patch paler and reduced or absent. The reddish-gold tails on the hind-wings add to its charms. The legs are a striking white, resembling starched white sport socks.
The Brown Hairstreak is the largest hairstreak in Ireland and is not common here or in Britain (we have three hairstreaks; the Green Hairstreak and Purple Hairstreak are the others). In Ireland it is mainly found in the Burren in Clare and Galway, with a small population in west Tipperary and west of Lough Corrib, County Galway. In Britain it is mainly found further south, in south-west Wales, southern, south-west and south central England with a small population in the east, in Lincolnshire.
The butterfly is single-brooded, flying from late July to mid-September. It breeds on hedges, scrub and woodland edges. It needs an extensive area of untidy, lightly or rarely managed habitat containing its larval host-plant, Common Blackthorn. Where it inhabits climax woodland the adult is rarely seen because it keeps to the tree-tops. In this habitat, such as in Garryland Wood, Galway, it frequents Common Ash trees where it feeds on the aphid ‘honeydew’, secreted by aphids feeding on the leaves. This sticky substance coats the leaves when aphids are in abundance, so the adults do not need to descend to feed on nectar. In years when the aphid secretions are ample, woodland males are rarely observed.
Adults mate early in the day. The rest of the day is mainly spent feeding and basking. It appears to be a very lazy butterfly; it flies infrequently, preferring to walk from one food source to the next. Strong wind does not appear to dislodge them. Males occasionally chase each other, but often they ignore each other and mated females. Later in the flight period, typically from mid-August, females disperse to lay eggs on low-growing Common Blackthorn. This is when most sighting opportunities occur. Even then, females do not advertise their presence. Egg-laying females crawl into the interior of a plant probing the surface of young stems for a suitable point, often at the base of a fork, bud or spine, to place her white egg. Occasionally she will deposit two or even three, but usually a single egg is laid before she flies away to seek another food-plant. When moving to seek new larval food-plants, she will sometimes cross open ground, and fly well above head height, making the butterfly hard to spot. Plants favoured for egg-laying are often young, and are in sheltered and unshaded locations.
The egg has a pitted surface, resembling a golf ball. Although a sharp white, it is not easy to find until leaf fall. Then it comes into its own! It stands out against the dark twigs, even in low light. The eggs are usually placed below 1.5 metres above ground (although sometimes higher; I observed egg-laying three metres above ground in Tipperary). The eggs are laid from mid-August to mid-September and remain unhatched until leaf burst in April. However, eggs remain on the plant after hatching because the larva only bites a whole in the tough shell to emerge from. I have seen eggs remain on a plant for two years, a testament to their durability.
The larvae are mainly green with diagonal white lines. The larva is slug-like in its shape and, like the rather languid adult, sluggish in its movements. In keeping with the adult’s elusiveness, the larva is mainly nocturnal and very hard to find. The pupa too is concealed. It is formed in June or early July, probably in a crack in the soil or beneath leaf litter or within grass tussocks. It is likely that the pupa has an association with ants.
Where the general landscape’s hedges and scrub are lightly managed over time, annual egg surveys pose interesting questions about the breeding requirements of the species. For example, breeding sites can receive fewer eggs over time before these eventually fall out of use. Identifying the reasons for this will add to knowledge of the butterfly’s requirements. Reasons for selection of breeding sites are not easy to determine. In the Burren where tall trees are scarce or absent, the adult feeds low down on hedges containing flowering bramble. While the butterfly breeds on these hedges some adult feeding areas are not used for breeding, even though the larval food-plants and aspect appear suitable.
Last weekend I snatched a couple of hours from an onerous schedule to do a quick egg-hunt at Gortlecka, in the Burren National Park in Clare. On a wonderful mild afternoon I searched a south facing hedge and adjoining patch of scrub where I saw a female lay an egg in August. Within a 20 metre long section of young blackthorn scrub/hedge I found 16 eggs, a couple just 30 cm above the ground. Fifteen eggs were laid at or close to the base of a lateral shoot with one laid slightly further up the side shoot, above three buds. This patch of scrub has developed in the past five years and this is the first time I have found eggs here, although I found eggs on the adjoining hedge in previous years. Despite annual searches over more than a decade I have not found eggs on a west facing hedge very close by, despite seeing females here last August, and in most years from the early 2000’s; however, I have found eggs on west facing scrub elsewhere at Gortlecka. Why it behaves like this is unclear but it is reassuring that the butterfly continues to thrive where I first saw it in the late 1990’s.
Regarding conservation, the species is highly vulnerable to extreme and regular cutting of hedges. While opening up rides in darkening woodland and then allowing plants to re-grow helps the species, annual flailing of hedges is very damaging, as most eggs are laid at the edge of a hedge. In areas where it occurs, rotational cutting should be applied, with large sections, around two-thirds, uncut in any year. It is important to retain patches of young scrub growing a short distance from a hedge or wood edge, as young plants are often favoured by our rarest hairstreak.
Why are many butterfly lovers so taken with this butterfly? Like many obsessions, the reasons for it may be obscure, but the elusiveness of the adult juxtaposed with the visibility of the egg might be something to do with it. So might timing. What else can a lover of butterflies do during the barren, bleak , unforgiving months from November to March? Egg hunts provide a badly needed outlet for pent-up desire, as well as offering an insight into how well the population is performing.
October is, in fact, not renowned for butterflies or moths.
Mild October weather will see some Red Admirals, Small Tortoiseshells, Commas, Speckled Woods, and the very occasional Peacock visiting gardens for over-ripe fruit and hedges for over-ripe berries and late nectar. Painted Lady butterflies can sometimes be found, usually at the coast. Occasional Small Whites and Large Whites will hatch in October instead of over-wintering in their pupae, proving eye-catching at this time of year. In some years a small number of Holly Blue butterflies will show up in warmer parts of the country, such as in Dublin, near the coast, and will be found on Common Ivy, its main food plant at this time of year. You might even stumble on a late Small Copper on a patch of patchily vegetated peat or eroding sand dune, absorbing the thinning autumn sunshine.
Of these, the most reliable butterflies at this time of year are Red Admirals and Small Tortoiseshells, usually flying quite high or basking on a south facing wall.
But all of these butterflies really belong to spring and summer. Autumn is their twilight home, very much an abode of last resort. Now they are no longer wide-ranging and carefree, restricted by diminished nectar and declining temperatures. Autumn is neither their era nor friend. While many of us enjoy the rich colour autumn brings to the landscape, this will be ripped down by November storms. You will wake to see summer’s leafy temple torn down; gone are the golds, russets, rich reds and purples; left are the gnarled bony boughs. And the butterflies are gone too.
Autumn can deceive the nature-lover, and nature. Some plants will produce a second set of flowers. And sow thistles, those tall, plants with showy golden flowers continue to shine, while late Devil’s-bit Scabious blossom, now looking darker blue, lend the illusion of a continuing bounty. The ivy flowers continue to ooze fat globules of sweetness and are heavily frequented by bees and wasps. Struck by this illusion of unending summer, the poet John Keats in his masterpiece “To Autumn” describes how autumn conspires with the sun to
“set budding more, /And still more later flowers for the bees/Until they think warm days will never cease / For Summer has o’er-brimm’d their clammy cells”.
The richly sensuous nature of this imagery, the appeal to sight (budding, flowers, bees) and the tactile sense (warm, clammy) create a rich, reassuring vista in which the seasonal shift is bare perceptible.
Yet winter is on its way, and Keats knew it. He closes his poem with references to the advancing season:
“And the red-breast whistles from a garden-croft/And gathering swallows twitter in the skies”.
Butterflies too must prepare for the cold months. In autumn most Red Admiral and most likely all Painted Lady butterflies move south across the seas, chasing the sun and resources fast fading here. The Peacock and Small Tortoiseshell will stay put, hiding from the cold in cool, dry recesses. These two play the long game, delaying breeding until better days come in the following year. The Large and Small Whites, Speckled Woods, Holly Blues and Small Coppers that emerged late, deceived by the autumn sun perish in the wind and rain but some get the chance to leave eggs behind. These must hatch and develop swiftly to have any chance of adulthood.
But most of our butterflies exist over winter in the least demanding, low-maintenance forms. Some are tucked up in their pupae, others stay in the egg stage while the rest are either small caterpillars or caterpillars that have finished feeding. These survival strategies get them through the lean months, especially November, December, January and February. In years with cold springs, winter survival strategies are maintained until conditions improve. Our butterflies are resilient, well-adapted to our seasons. All they need is good homes.
Unlike our butterflies, there are moths that specialise in flying during October. For some moths, October is their time. Some are beautiful, but rarely seen. The Herald, named for the heraldic appearance, prepare to over-winter as an adult by feeding on ivy flowers and extra-ripe blackberries. The Herald is a well-built long-lived species, which can be found from September to June. This lovely insect will spend the hostile months in your attic, sometimes in large groups. Another autumn beauty is the Merveille du Jour, the freshly hatched moth green and flecked with black. Unlike The Herald, this creature breeds in autumn, leaving its eggs to spend the winter on oak twigs. For its distinctive moths, October has its benefits!
Lullybeg’s Crabtree Reserve continues to produce good numbers of butterflies well into September, despite the often disappointing weather since late July.
Sunday saw some stunning conditions and Red Admirals, many very recently emerged, were observed feeding on Devil’s-bit Scabious, one of Lullybeg’s best nectar sources and certainly the best autumn food source for the reserve’s butterfly, moth, bee and hoverfly populations.
There were significantly fewer Red Admirals than earlier in the month, but this points to migration; at this time of the year, Red Admirals, after feeding up for a few days after emerging, head across the seas to breed further south where temperatures and larval food plants are more suitable. The individuals still present are mainly later emergents and will leave in their turn. However, already their basking behaviour differs from that observed in early September. When direct sunshine was interrupted by a cloudy then, the Red Admirals continued to feed initially, but then left the flower to bask, often on the ground or low down to recover heat lost while feeding during a cloudy interval. Towards the end of the month the butterflies leave the flower shortly after it clouds over to seek cover or to bask higher up, such as on a tree trunk, to catch the light when the sunshine returns, especially in the afternoon when shadows lengthen. Basking by Red Admirals on trees is often observed in late September and October; as the sun’s angle becomes lower, the butterfly basks higher up. Luckily it finds food on trees that contain Common Ivy, a valuable late autumn nectar source. Humble and even unloved it may be, ivy is a banquet for insects flying late in the year. In overcast but mild conditions, Red Admirals are capable of remaining active. Because of this ability it can fly during mild conditions even in mid-winter. The butterfly only needs direct sunshine to maintain activity when air temperatures are cool.
Brimstones were also on the wing, enjoying the Devil’s-bit Scabious nectar in the lovely autumn sunshine. Here the benefits of the lower autumn light can be seen; it passes through the golden male Brimstone’s wings, showing an intense purity, like holding up a jar of honey to view with the sun shining through it. In fact, the colour of the Brimstone appears liquid, a fluid intensity that one almost expects to see leak golden light! In short, a photograph of a back-lit Brimstone is a must-have!
Another busy butterfly is the Small Tortoiseshell. Like the Brimstone he is feeding in advance of over-wintering in its adult incarnation; unlike the Brimstone which seeks a leafy sanctuary such as that afforded by Common Ivy, Common Holy and bramble, it seeks dark, often pitch black winter quarters. The Brimstone is more vulnerable to paralysis when the sun stops shining. It very swiftly loses the ability to fly when direct sunshine is terminated while the Small Tortoiseshell can fly in dull but mild conditions. This explains the longer flight season of the Small Tortoiseshell in Ireland, and why it is found throughout the country while the Brimstone does not occur in north Leinster or Ulster.
Speckled Woods were about in fair numbers last Sunday. The autumn brood of this woodland and hedgerow butterfly, whose numbers peak around mid-September, is often very large and for a week or two it seems that summer is not over at all! Sadly, this boom passes quickly, and numbers are now thinning out…
A few Green-veined Whites, representing a partial third brood put in an appearance. One male Green-veined White tormented a male Brimstone. The rather annoyed Brimstone did his best to shake off the unwelcome attention by flying erratically, and by gaining height; Green-veined Whites rarely fly at tree-top level. This one did. The Brimstone then tumbled downwards pursued by his amorous pest until I netted both and released one, then the other. The likely end to this scenario was avian attack and I was in an interfering mood. However, the male Green-veined White was fairly exhausted by his efforts, and needed a rest to bask and recover lost body heat. Both protagonists are pictured here, after the incident.
Butterfly Conservation Ireland attempted to contact the National Parks and Wildlife personnel responsible for the region in which Killeglan Grasslands is located to check if the site was damaged or about to be damaged. This issue is referred to in a previous post.
After several phone calls and over a week after our concerns were relayed, we were contacted and a site visit was made by the person responsible for checking on designated sites in that area. We were told that the damage done bordering the site took place some (unspecified )time ago and that the piling up of stone on the SAC was carried out several years ago and is that noted in the site description published on the National Parks and Wildlife website.
Butterfly Conservation Ireland expressed its concern to the official about the failure to respond to our message and about the time taken to deal with the issue. The National Parks and Wildlife staff have the crucial role of monitoring our designated sites which contain our best natural habitats. The delay in responding might see irreparable damage caused.
We hope that our special places receive the protection they need, and that the National Parks and Wildlife Service is given the resources, management and support needed. Above all, we will continue to press for the fullest commitment to nature conservation by the staff of the organisation.
Enormous destruction of Ireland’s natural heritage took place especially from the 1970’s. Unless we show we really are serious about defending remaining patches, we will have nothing left to protect.