The fascinating and surely one of the greatest mimics in the moth world, the Narrow-bordered Bee Hawkmoth has been found in the Cooley Mountains by Enda Flynn and his son Ciaran, both keen observers of butterfly and moth populations in their area. The moth was observed feeding on lousewort, probably Common Lousewort Pedicularis sylvatica. This moth is rare in the east of Ireland, currently unknown in Meath, Dublin, Wicklow, Wexford, Carlow, Kilkenny, Laois and until now, Louth. The number of observers in Dublin, Wicklow and Wexford is high so it is unlikely to have been missed, as it is a large, bumblebee-sized day-flying moth.
The benefits of close observation have paid off in the case of County Louth. If you see this lovely moth, which flies in April, May and June we’d love to hear from you. Let us know where and when you saw it by contacting us at email@example.com.
Some adult butterflies enjoy what is for insects a long life. Peacock, Comma (over-wintering generation), Small Tortoiseshell (over-wintering generation) and Brimstone live long adult lives. Many other butterflies live around a month.
Some butterflies do not have this longevity. They must grab every moment of warmth to feed, mate and lay eggs. One short-lived butterfly is the Marsh Fritillary butterfly, a highly localised species. It has, for example, just one known breeding site in County Dublin. I spent Sunday afternoon on June 9th observing the colony watching it avail of the sunny conditions to breed. In the next day or so, many of the butterflies you see below will be dead.
The first priority of the male is to warm up in the morning sun. Both sexes bask with wings fully extended, usually on dry grass. It takes a while for the butterfly to absorb the heat it needs making it fairly easy to approach. When warm enough the male embarks on his search for an unmated female, quartering low over the turf. These searches are punctuated by pit-stops for refuelling at buttercups, tormentil, orchids or any flower available. Males frequently clash, and a posse of four or more chasing each other is a common sight on well-populated areas. Sometimes the male will adopt a sit and watch strategy, perching on a taller piece of vegetation until a butterfly appears. He then dashes out to check who it is. It could be a female.
The newly-emerged female Marsh Fritillary frequently sits on the surface close to where she hatched and wait to be discovered by a male. Only rarely will a virgin female fly, and then only when conditions are very warm. The reason for this lack of activity is her weight. A newly hatched female is packed with hundreds of developed eggs, weighing her down. As a short-lived species, it is vital that the eggs are laid as quickly as possible. But for that to happen she needs to mate.
When found, she makes no attempt, like the female Peacock or Small Tortoiseshell at playing “hard to get”. The females of these two species put males through their paces, flying at bursts of speed to see if he can keep up. They even try to shake her suitor off by hiding and by flying directly into the territory of other males who attack him or join the chase! Nothing like a choice of mates and healthy competition for these females!
Our female Marsh Fritillary has no time for games. She succumbs immediately. After being joined for perhaps 45 minutes, mating is complete. However, to make sure she remains mated only by him, the male seals her to prevent a future mating.
Heavily weighed down, she flutters short distances to seek a good place for her eggs. In cooler weather, she will crawl over the vegetation to search for an egg-site. Finally, she finds a suitable Devil’s-bit Scabious leaf, usually surrounded by well-developed tufted grasses that contain dry leaf litter. The foodplant will be unshaded and often south-facing. Gripping the edge of the leaf, she curls her abdomen to the underside of the leaf and lays her eggs on one side of the leaf, left or right of the mid-rib. It takes her the best part of an hour to glue her eggs on the leaf and onto eggs she laid earlier.
When done, her body looks like a flabby bag. But she is much lighter having laid, typically, 200-300 eggs. She can now fly properly, is much more agile, She visits flowers, repels male attention and basks. If the weather is hot, she may leave her colony to seek new breeding territory. If she is lucky, she will live long enough to develop more eggs, which are fertilised by the sperm she obtained when she mated. Her second or even third egg batch will be smaller than her first.
As for the male, he will continue to look for newly emerged females. He has many hazards-dragonflies, birds, spiders and bad weather account for those unaccounted for by old age.
The Marsh Fritillary lives its short life on exposed grasslands of various types and is therefore vulnerable to bad weather during its flight period in May and June. But every year, enough of them manage to seize that one good weather day to lay down the next generation. As long as we protect its habitats, this lovely butterfly will continue its battle with its short adult life-span, fierce Irish weather and the range of predators that teem on its species-rich homes.
Clongawny is just outside Mullingar, not far from the N4. The visited sites lie north and south of the Royal Canal and are quite different. One is calcareous grassland on the steep bank above the canal while the other is a low-lying area of wet, boggy grassland.
We met at the car park near the high bank and set off for the damp grassland first; it is very exposed offering no shelter against the expected rain shower. We needed to catch the sun while we had it. The site was discovered to hold a large Marsh Fritillary colony two years ago. Local Butterfly Conservation Ireland members Lesley Whiteside and Richella Duggan monitor the site. Some scrub was cut and an invasive grass, Reed Canary-grass, was mechanically controlled. Waterways Ireland were notified and an agreement reached that the site’s main nectar resource area would not be mown during the Marsh Fritillary flight period.
In 1902 an observer named Middleton reported a Marsh Fritillary population explosion in the Mullingar area. The general landscape has greatly changed since those heady days but we were keen to see how the present-day population is faring.
The site certainly does not have the look of a classic Marsh Fritillary site. Most colonies breed on areas where the Devil’s-bit Scabious, the larval foodplant, is very visible as well as abundant. However, even when standing on the site it is hard to see the Devil’s-bit Scabious. The most obvious characteristic of the site is the dominance of rank grasses. It is only in late summer when the scabious is in bloom that the extent of its abundance becomes clear. The site does have a southerly aspect, a characteristic that is frequently important for the butterfly.
Our group consisted of around 20 people ranging from the very young to the young at heart-great to see interest in nature shared across the demographic! We walked on the main track through the site and Marsh Fritillaries soon zoomed in-and-out- of view. Males are tricky to follow in flight as they are very active in the sunshine, darting erratically across the grassland, plummeting when a stiff blast of blustery wind pushes it back. Fortune favoured close inspection-the sun was intermittent causing males to land and bask on vegetation. Phones, as well as cameras, were used to take photographs. Some butterflies quietly perched on hands when encouraged, offering great close-ups of this highly local species. A few Cryptic Wood Whites fluttered laboriously around the site, occasionally pestered by urgent fritillaries. There was not much in flower for the butterflies to feed on. A few tiny tormentils, buttercups and a few clumps of Kingcup (the first time I’ve seen this fritillary use the plant) were really all there was but the butterflies were active regardless.
After we walked the site, we rejoined the towpath and continued east for around 150 metres and entered the edge of the local bog. Here there is a transition zone between raised bog and damp grassland that contains an obvious abundance of Devil’s-bit Scabious and, in the driest areas, Common Bird’s-foot-trefoil. Patches of scrub provide shelter. A really dense colony of Marsh Fritillary was found here. Common Blue, Burnet Companion moth and Common Heath were recorded too. The frenetic activity of the Marsh Fritillary here created great interest and it is a lovely and interesting area to linger at.
But we re-traced our steps to get our lunch. Lesley’s delicious cookies were delicious! Hot tea and cookies fortified us for the high bank which is awash with vetches, trefoil, hawkbits, orchids and in parts, Kidney Vetch, a rare plant in this area. The sunny track here is great for Dingy Skipper, Common Blue and Cryptic Wood White. We enjoyed watching a lovely ‘blue’ female lay on Common Bird’s-foot-trefoil before darting decisively down the track to seek, no doubt, fresh breeding ground.
We then headed home, happy that the Marsh Fritillary is still in the Mullingar area 117 years after it was reported as a local plague! It is very unlikely we will ever see mass populations again given the damage done to the natural landscape but at least we know where to find the species, and we have local people who care for the butterfly and take the steps needed to keep the butterfly happy.
A special thanks to the event organisers and everyone who came to the event, and in particular to the Baltrasna Environmental Group who take such care of and pride in their wild places.
“All the bright precious things fade so fast. And they don’t come back”. (Baz Luhrmann: The Great Gatsby 2013)
One of the sweetest pleasures of the butterfly lover is to see a perfect, freshly emerged butterfly. When it pushes its way out of its chrysalis and dries and expands its wings, the new butterfly perches in the open. Most butterflies then bask, with wings open, to warm up. If you are lucky, you can see these brand new insects, showing perfection to the sun.
This butterfly has yet to have any of its silken glow tarnished. It has not brushed up against vegetation. It has not pursued or been chased by a mate. It has not had its colours bleached by the sun. He has yet to fight another male to hold a territory. She has not yet lost wing scales crawling around larval host plants to seek out a suitable egg site. No bird has taken a peck at a wing, no dragonfly assault has torn a wing. No sharp gust has attacked, no rain has pelted at its colour of the perfection of the wing margin. The delicately scalloped wing edge, the outer hair fringe-all breathtakingly pristine.
But life does not stay still for anyone and for a brief butterfly life to have meaning the butterfly must take to her air and fulfil its destiny. He is born to find as many mates as he can. She is born to lay as many eggs as she can in the best places she can find. She will not lay on just any food plants, she is choosy, selecting only the best plants in the choicest locations. She will test the site around the host plant, she may check it to make sure no-one else has laid eggs there before her. She tests the temperature and nutritional quality of the plant.
These activities remove the delicate scales and fray the wing edges. Mindful of this damage, many butterfly collectors bred specimens in captivity to obtain perfect specimens, quickly killing the newly emerged butterfly before it loses any of its perfection. Even in butterflies that are long-lived, such as the Peacock butterfly, which can live ten months or occasionally a month more, the intense, sharp definition and colour pales quickly. Colour washes out; the deep mahogany-red ground colour of the upper sides dulls quickly. Tiny scars appear. It loses that ‘wow’ factor.
Short-lived butterflies, such as the Marsh Fritillary, which has one of the shortest adult life-spans of any of our butterflies, is elaborately patterned. The brick-reds, creams, yellows are set in various shapes on a dark background. On the more extreme examples, the ground colour is coal black. This enhances the contrast with the bright colours, giving a stronger definition. Within a day, scale loss gives this butterfly a greasy look, a mockery of its pristine glory. It spent around 6 weeks as an egg, ten arduous months as a caterpillar and two weeks as a chrysalis to reach its ultimate state just to lose its glory after the first day as a winged insect.
As a metaphor for human life, the message is clear. Our fate reflected in a butterfly’s, even though it is played out over a longer time. However, we live in an era of greatly increased longevity compared with a century ago. So perhaps we appreciate the beauty of a newly hatched butterfly not just for the extravagant colours and patterns but also for the ephemerality of the display. We sadly have another reason to appreciate beauty today-rarity. Many species are much less likely to be seen today-partly because we have grown distant from nature but also because of the retreat of butterflies underway in the modern landscape. As early as the 1930s Frederick Frohawk, one of the greatest of the English lepidopterists, warned that the countryside in England was becoming less accommodating to butterflies. Frowhawk died in 1946, before the post-war onslaught of chemical inputs in agriculture. He would be appalled if he could see the British countryside today.
We don’t need to go back that far in Ireland. The changes since 1980 have been immense. Large areas of the landscape have simply been destroyed. And many of these changes are irreversible. Large areas of the Burren (though thankfully, most of it remains) have been destroyed. Most of our raised bogs are extinct. Most semi-natural grassland has been obliterated by ploughing, re-seeding, the input of fertilisers, pesticides and herbicides, drainage, abandonment, construction, afforestation, quarrying, over-grazing, etc.
It is not sustainable to live the way we are, so far from nature that we feel immune to change. What has happened to our butterflies may one day happen to us. That metaphor may be more meaningful than we want it to be.
We have seen a large surge in the membership of Butterfly Conservation Ireland in the last two years. We are a voice to express your love of and concern for our wild places and the wild creatures that rely on these places. Please continue your support for Butterfly Conservation Ireland so that we can continue to demand that our landscape is respected. Otherwise, the beauty of the sensitive species like the Marsh Fritillary, and what it has to teach us about ourselves and the quality of our environment, may not be there to delight and intrigue.
Lepidoptera events depend on the right weather and moth-trapping is no exception While butterflies need direct sunshine, most moths are nocturnal and overcast nights are what these moths prefer. Even heavy rain will not deter moths provided the night is mild.
Fortunately for our efforts to trap moths (under licence from the National Parks and Wildlife Service), Friday night was calm and mild and when we arrived to open the traps on Saturday morning, we were rewarded with a great range of species and great numbers. Philip Strickland, Butterfly Conservation Ireland’s moth specialist identified the moths, including the tiny micro-moths. Among the species were Fox Moth, Emperor moth, Eyed Hawkmoth, Poplar Hawkmoth, Lesser Swallow Prominent, Pebble Hook-tip, Scalloped Hook-tip, Green Silver-lines, a rather late Common Quaker and Clouded Drab, a lovely Lunar Thorn, Muslin moths, Grey Pine, Spruce, Broken-barred and Green Carpets, to name a few. Some quite scarce species, such as Grey Birch, of which there were around six individuals, also featured. The Beautiful Snouts looked perfect, almost as if they were smartly and formally attired for an official engagement.
We got plenty of photographs especially of the larger moths, most of these proving very docile. While butterflies are so obviously striking and easy to see and admire, moths are just as elegant but harder to find. It is great to see the pleasure the moths’ beauty gave to everyone present and although this has been said on this website many times before, it is the people who attend our events who render the experience of nature even more special. Hearing the views of people regarding a moth or butterfly they have seen for the first time offers new insights and fresh excitement. For those who are familiar with a particular species, the excitement of another’s discovery refreshes enthusiasm, imbuing the familiar with new wonder.
The location of the trapping, in high-quality bog woodland under birch woodland among bilberry and heather with other habitats nearby draws in a range of moths. The intricacy and range of the markings (check the Emperor), the ingenuity of the wing outline (lovely scalloped edges on several moths), the variety of shapes and the sheer number of species all packed in together creates a fascination that is hard to absorb at one event. We hope you enjoy the photographs below.
After adjourning to the Heritage Park cafe for refreshments we set out for famous Lullymore West cutover bog to check the day-flyers. Alas, the sun was lacking; it was damp and seemed unpromising. However, careful searching did yield some good results. While not very active, we saw a number of diurnal moths and perched butterflies. Marsh Fritillary, Cryptic Wood White and Narrow-bordered Bee Hawkmoth were highlights. We had to encourage the Marsh Fritillaries to open their wings by letting them perch on warm human hands. The Cryptic Wood Whites did fly but not anything like as persistently as their typical habit. One of the advantages of butterfly hunting in very high-quality habitat in dull weather is that when a butterfly is found, you can get really close to it. In hot weather close observation is impossible.
We thank everyone who attended. I hope everyone enjoyed the experience as much as we did.
Leaden skies with some bright patches offered hope for at least a dry spell for our Bull Island outing today. We assembled at the roundabout (luckily I brought my net as an identification point!) and headed north along a sandy track. Deep pink Common Vetch and splashes of buttercup flowers gave a sharp contrast against the muted green of the wall of grasses that edges the path but little else was in bloom.
We reached the ‘Alder marsh’, which was very dry, and soon Marsh Fritillary larvae were observed. These were fully grown and sluggish or stationary. Most were on dry grass, some on the foodplant, the Devil’s-bit Scabious. Most of the larvae will have pupated and a few adult butterflies may have emerged but the sun needed to coax any that have reached adulthood did not appear. The larvae remaining are most likely infected by a parasitoid wasp that prolongs the larval stage so that the wasp can delay its own emergence to coincide with the availability of the next generation of Marsh Fritillary larvae which will be present after mid-July. We eventually found a chrysalis, in the open, attached to the upper surface of a foodplant leaf (an untypical pupation site). A Drinker Moth larva, a Common Lizard and a delightful and stunning Cinnabar Moth were found. We managed to place the moth it in a jar where it eventually settled for a photo shoot!
The Marsh Fritillary breeding site is in excellent condition. The sward is open, contains a range of heights and has a high density of foodplant growing among dry, warm sward litter, ideal for larval basking. There is plenty of nectar on the way, with Common Bird’s-foot-trefoil beginning to flower. Cutting and removal of the highly invasive Sea Buckthorn has also improved the habitat-congratulations are due to the site managers for this vital conservation intervention.
It would have been wonderful to see the beautifully patterned adults but we might see them next weekend at Lullymore. It was a lovely day for conversation and it was lovely to be in such a warm and engaging company. The constant singing of the skylarks provided a delightful atmosphere. The view from the marsh looking northwards to Howth is uninterrupted rural Dublin at its finest. You’d never think the capital city is just behind you!
Thank you for everyone who joined our outing and made it special.
At this time of year, the Burren in Counties Clare and Galway is a rewarding place for any butterfly enthusiast. The Burren, an area of exposed carboniferous limestone contains the best habitats in Ireland for most of Ireland’s butterflies, including many of our rarest species.
Much of the Burren remains unspoilt by modern farming. The ground is largely inaccessible to modern machinery and much of the region is legally protected by the designations under the Habitats’ Directive.
The warm limestone and fertile soil pockets produce a wide range of plants that moths and butterflies need for nectar and food for their larvae.
The main habitats for butterflies in the Burren are open scrub and woodland on limestone, limestone pavement with pockets of soil and open limestone grassland. Areas of heathland and species-rich wetland also exist.
I spent much of last Saturday enjoying the butterflies that live in an especially warm, dry, sheltered area near Clooncoose valley containing open limestone pavement, patchy open scrub backed by tall scrub. The air temperature barely reached about 14 Celsius making this warm site the ideal spot to look for these newly-emerging spring species. This is one of my reliable spots, where year after year I am guaranteed to see my target butterflies.
I did not see the Pearl-bordered Fritillary anywhere else in Clooncoose valley that day. I knew the ‘Pearl’ must be running late this year. In 2009 I saw it in numbers in the valley as it abounded in the glorious heat of April that year. But this lovely creature is highly variable in its emergence. The pupa can last a little over a week when the weather is good but the pupal stage can last a month, perhaps longer, in cold weather.
Fortunately, I saw three pristine males. They spent time basking quite frequently between low patrolling flights and the occasional brief pause to feed on the golden Common Bird’s-foot-trefoil blooms. The orange-red wings of this butterfly are a sharp neon on the soft grey limestone and really needs to be admired. This is our rarest native resident and is so specialised there seems little chance of it expanding its distribution in Ireland.
A less dramatic butterfly, the Wood White, also flies low to the ground but instead of the rapid flight of the Pearl-bordered Fritillary, you will notice a feeble, floppy flight. It looks as though it will float to the ground, depleted of vigour but it shows an unexpected resilience for a dainty flyer by staying airborne for long periods. This delicate white is somewhat less restricted in its distribution but is confined to scrub and woods on limestone habitats in Clare, Galway and perhaps Mayo.
A third butterfly, much more widespread than the previous two species, is the Dingy Skipper. In the Burren, this moth-like butterfly is represented by a subspecies, baynesi which is unique to the area. It is paler than the Dingy Skippers found elsewhere. Its paleness helps it to melt into the limestone, aiding its blending ability. This subspecies is recognised widely as a distinct butterfly. The Dingy Skippers I observed were darting about, chasing each other and the Pearl-bordered Fritillaries, all eager to locate a mate.
Interestingly, I saw only one female Dingy Skipper and no female Wood White or Pearl-bordered Fritillary, suggesting that we are very early in the flight period of all three, as the earliest females typically start to emerge a day or two after the first males appear.
Later, two new Small Coppers appeared, their shiny copper adding their glamour to the scene.
All these species have in common a liking for warm, dry well-drained ground found in the Burren, our greatest butterfly haven. If you want to see these butterflies, visit in good weather during May.
Occasionally we experience enormous influxes of the Painted Lady, a migrant that originates in North Africa or perhaps the Middle East. We had millions reaching our shores in 2009 after a huge build up in Morocco saw a mass migration to Spain. These produced a huge generation in Spain that moved north and arrived in Britain and Ireland in late May and early June 2009. These produced a native generation in these islands that migrated south in September.
Butterfly Conservation Ireland member John Lovatt reports on a mass migration event that has just taken place in Cyprus. It is being speculated that these came from Kuwait. The vegetation in Cyprus is currently ideal for butterfly breeding as the rains have been plentiful there this winter. Will the offspring of these Painted Ladies arrive in Ireland in early summer? Time will tell…
Painted Lady Migration from 21st March-9th April 2919 in Famagusta “county”, Greek Cyprus
I have repeated a visit to the same Gkreko district in Famagusta for the past seven years in March/April to observe bird migration.
This year I witnessed an unprecedented large migration of Painted Lady butterflies. There were small numbers seen daily from 17th March which would be the norm at this time of year.
On 21st March there was an invasion of Painted Ladies which one might liken to what might be expected with locusts. Clouds of butterflies arrived constantly all day. There were around 100 butterflies in front of me and the same number on both sides and behind me. To look beyond, the same numbers were everywhere as far as I could observe. I estimated at least a million on the Gkreko Head district and when at Paralimni about eight km. distant, there was a similar migration. I later learned at Nicosia there were unprecedented numbers there. This information came from a well-respected bird watcher. I later heard there were large numbers at Pafos, a two-hour drive away to the west. It must be reasonable to consider the large numbers were present all along the south coast and into the Turkish south coast on the panhandle to the east.
It was considered five million butterflies in the whole Famagusta district to Nicosia would be a conservative estimate. This would only be section of the whole migration along all the coast.
Numbers continue to arrive but in much lower numbers of 30/300k daily up to the 8th April. On the 8th April there was another large invasion, but not like the 21st March, with perhaps a million estimated in the Gkreko district.
There were a few Painted Lady butterflies observed which were about two thirds the size of the usual ones observed.
There was a large dragonfly migration at the same time, but nothing like the butterfly numbers. Clouded Yellow butterflies were also present, but perhaps ten to 20 seen daily.
In all, it has been a remarkable experience that has amazed the population of Cyprus, not simply nature lovers.
A sharp easterly wind is keeping the butterflies grounded on Lullybeg Butterfly Reserve in Lullybeg, County Kildare. So far in 2019, we have spotted Brimstones, Small Tortoiseshells and Peacocks.
We await Orange-tips, Green-veined Whites, Speckled Woods and Common Heath moths which we expect at this time of year. All we need now is good weather.
There has been an extensive management programme undertaken since last summer and the results are very keenly awaited. Grazing on part of the northern section, mechanical removal of very dense scrub to extend high-quality grassland habitat and manual removal of scrub on an area on the southern side of the reserve by our members has really extended opportunities for the reserve’s butterflies and moths.
We can report that the Marsh Fritillary is really thriving. Over forty nests (many containing hundreds of larvae) survived the winter and many, if not all the caterpillars are now in their fifth or even sixth instar growth stage (there are six instar stages in this species’ larvae). Over the next three weeks, healthy larvae will enter the sixth instar followed by pupation. Fingers crossed we will see outstanding numbers of this gorgeous butterfly darting around in late May and during June.
A nice surprise is the re-discovery on the reserve of the beautiful day-flying Wood Tiger moth. A larva was seen on a Devil’s-bit Scabious leaf (see below). This moth is rated Near Threatened on the Moth Red List (Ireland Red List No. 9 Macro-moths (Lepidoptera)). This record may be the first county record for Kildare, although the larva was found on the reserve about five years ago. The larva seen on April 13th was in a newly cleared area, so we are hopeful that it will increase here.
Other scarce moths found on the reserve are the Small Purple-barred, also Near Threatened. This species has a strong population at Lullybeg. This attractive day-flyer is usually found on unimproved calcareous grassland, limestone pavement and heath, but here it is, on cutover bog! We also have Narrow-bordered Five-spot Burnet moth, ranked Vulnerable on the Moth List.
Over the coming months, a close watch on all of these species will be kept. We hope our efforts to maintain the special habitats here will meet the needs of the rare moths and butterflies that rely on the habitats at Lullybeg, as well as the more widespread species.
The butterfly larval stage is the growth stage for butterflies and moths. It is a highly sensitive stage highly vulnerable to disease, starvation, predation, infection by parasites and failure to thrive if environmental conditions turn hostile.
According to Newland et al. (2015) many adult butterflies live long enough to lay about 50 eggs. Of these, 20-40 might become caterpillars of which perhaps 10 will become chrysalises. Just 1-3 adults will be produced.
In these calculations, the highest numerical loss is seen in the larval stage. What do larvae do to avoid being eaten?
There are essentially two phenotypes (concerning the appearance of an organism arising from the relationship of its genetic makeup with the nature of its environment) used by Ireland’s butterfly larvae.
Some butterfly larvae are aposematic. This means that larvae are highly visible to send a warning signal that they are distasteful, toxic or painful to eat.
Such larvae do not attempt to hide or blend in with surroundings. These larvae feed openly, often in groups, unconcerned about an attack by birds. The larvae of the Large White, which are brashly obvious, are black, white and yellow. These are smooth-skinned but their bodies contain caustic mustard oils that will burn the mouth of a predator.
There are other aposematic larvae that are highly distasteful and painful to eat. The Marsh Fritillary larvae feed openly, in large groups until their final growth stages. The larvae are spiky, containing bristles and black, standing out when they bask on pale, dry leaf litter. The bristles are highly injurious. If you don’t believe me, try pressing one to your lips. Even doing so gently is quite unpleasant. If a bird does grab a spiky Marsh Fritillary, Peacock or Small Tortoiseshell larva, there is a chemical deterrent deployed which involves the larva placing its mouthparts against the bird’s beak and vomiting. The vile liquid (I’ve smelt it but not tasted it-yet!) provokes the bird to drop its prey.
If that is not enough, the larva also pushes its spines into the predator, causing it to recoil in pain and drop the larva.
Most of these larvae are quite unharmed when dropped and roll into a ball to present a forest of spikes in the event of another attempt on its life.
The larvae of other species are cryptic and rely on blending into their surroundings. These larvae are soft-skinned and edible, highly attractive to birds. Their colour often matches the food plant. Their behaviour is usually highly secretive.
One example of such a larva is the Purple Hairstreak. This species feeds on oak leaves and flowers. The egg hatches in March and April when the oak buds begin to open. The tiny larva enters the opening buds but when older and the leaves unfurl it must feed openly. During the day it rests at the base on the leaves, on leaf scales which it closely resembles in colour and patterning. In order to continue to blend in with the scales, it spins a loose web around these in case they are shed by the tree, ensuring these are retained.
Feeding is now carried out at night when birds are inactive. Another strategy is its remarkably slow movement which avoids drawing attention. When oak leaves are unfurling, small birds scour the trees in search of the myriad larvae that feed on oak leaves. While Purple Hairstreak larvae resting at the base of the leaves are found, the research suggests that about half of the larvae survive on oak leaves with predation greatly increasing after leaving the tree to pupate (Thomas 2010).
Another strategy used by the larva of the Purple Hairstreak is to play dead if disturbed by a bird. If it is picked up, the larva stays still. A wriggling larva is a clear confirmation that live protein has been found, while a still creature might be a leaf scale or piece of bark.
While the strategies described may protect some caterpillars from birds there are many other hazards. Many caterpillars are killed by bad weather, viruses, parasitoids and other predatorial animals, such as wasps.
When you see the perfect adult butterfly admire it not just for its beauty but for its achievement in getting this far!
Thomas, J. and Lewington, R. (2010) The Butterflies of Britain and Ireland. (Revised edition) British Wildlife Publishing, Dorset.
Newland, D., Still, R., Swash, A. and Tomlinson, D. (2015) Britain’s Butterflies (Third edition) Princeton University Press, New Jersey.