It is late August now, soon to be September. Since the third week in August we are seeing large numbers of newly emerged Painted Lady butterflies. How can we distinguish these from their immigrant parents? New emergents are far more vibrant in colour as well as lacking wear and tear. A feature of some fresh Painted Ladies is that the orange band on the upper-side of the forewing has a pinkish flush, a subtle but striking hue.
Here we have them, looking delightful and energetic, darting around flower patches at high speed, easily disturbed by an approach from a human observer and by each other. This behaviour is common in many newly emerged butterflies. These often look unsettled and no clear or obvious intention is apparent in many individuals. It is as if they are unfamiliar with everything, new to the world and unsure about how to behave.
Although it is difficult to say how every individual butterfly will behave, most Painted Lady butterflies will settle down to feed in a concentrated manner. They become less easily agitated and easier to approach. Then there will be time to get close views and good photographs to record your memories of this remarkable summer for this butterfly and the message it is giving us about our world. This switch in behaviour enables the butterflies to build up vital fat reserves for their next big step, their great reverse migration south. In 2009 in the area where I watch butterflies most often, the vast majority of the butterflies departed early in the second week in September. The chances are that you will wake up one day to find they have gone.
This year, this appears the most likely outcome. I have not seen any evidence of breeding among the new butterflies which indicates these are preparing to depart. While these are still present, go out in your garden, parks and anywhere there are flowers to see them. They are seemingly everywhere now and might be more numerous than the numbers that reached our shores this summer. In 2009 there were millions more reverse migrants than immigrants and this may be happening in 2019.
The Painted Ladies flying now look well developed. Many large specimens are present, evidence of high-quality larval foodplants. We had good temperatures and good moisture levels, especially during August. The Painted Lady butterflies flying around my garden at the moment took around 50 days (July 2nd to August 21st, seven weeks) to develop from egg to adult. It is not easy to say whether we have two native generations of the Painted Lady up to this point in the year but we definitely have one home-grown generation. Depending on the weather over the coming weeks, we may get a second generation arising from the immigrants that reached Ireland in late July and early August. This will give us another Painted Lady peak in late September. Until then, we will have to see if there is another chapter left in this remarkable story.
Our Burren walk on Sunday, August 4th met on the Green Road just past the turn for the Lough Avalla Loop Walk. The weather was very inclement. It rained very heavily within the hour before our start time of 2 pm. It offered the prospect of a wash-out.
We parked in a field and assembled. Would there be anything to see? An introductory talk on the Burren’s butterflies was followed by showing some moth specimens trapped at Carran the previous night and a Grayling caught in the morning sunshine and a beautiful male Wall Brown fortuitously caught in the field before the walk. Moths shown were the Dark Spectacle which was well-received-seen head-on, pale tufts resemble eye-glasses, creating amusement in our group. A yellow Scalloped Oak well-named for its scalloped edges but not for the oak which it does not resemble. Oak is a larval foodplant for the moth, but so far a number of trees. The Burren Green was a star, though, living up to its name by being a green moth confined to the Burren. The moth settled happily on one lady’s coat and refused to depart.
We proceeded to the nettle patch near the field edge. The nettles were very vigorous with hundreds of Small Tortoiseshell caterpillars from at least three growth stages (instars). Folded leaves were opened to show a solitary Red Admiral larva in each one. A thistle patch held Painted Lady caterpillars, feeding as quietly as the Red Admirals. The larvae and their behaviour received great attention from our enthusiastic group. The open feeding habits of the Small Tortoiseshell larva contrast sharply with the solitary, well-concealed strategy of its relatives-why is this? Do the Small Tortoiseshells need to bask openly to digest food? Are the softer-bodied Red Admiral and Painted Lady larvae more susceptible to being stung by parasitoid wasps? These are possible reasons for the different living arrangements.
A Ringlet and Meadow Brown butterfly were spotted and closely approached, their eye-spots providing a ready definer as members of the “brown” family. The placement of spots around or near wing edges deflects bird attacks away from the vulnerable head allowing the butterfly to escape with just a nip to the wing edge.
About an hour and forty minutes into our event, the swollen clouds burst. We closed our event but had seen a surprising amount for the weather we had. Thanks to everyone who made the trip. Everyone was very appreciative which made up for the damp conditions. Thanks also to John Marrinan for letting us park in his field and to the Burrenbeo Trust who helped to organise the well-attended event.
See the Burrenbeo Trust Facebook page for images of the event.
The Painted Lady migration over the last two weeks, first noted along the northern coasts is now being recorded in a range of places on the coasts of Ireland. Records of large numbers arriving have now been received from the Dublin, Wicklow and Kerry coasts. The butterflies are initially feeding in coastal locations, on flower-rich sand dunes and coastal gardens before moving inland. The butterfly is currently (August 8th 2019) abundant in Lullymore, Kildare, in the midlands. Presumably, it is present inland in many other flower-rich locations. The massive numbers are attracting widespread public attention and media interest.
What happens next?
The butterflies are now busy feeding. Some will disperse and migrate further, while others will settle down to breed here. If the weather remains warm, their offspring will probably reach the adult state in September. The previous Painted Lady influx in late June and early July breed; these larvae are now reaching their final growth stage and it is likely that some have pupated. These will hatch as adult butterflies in two-three weeks depending on temperature.
We could have overlapping generations in flight over the next six weeks. If the weather remains warm, it could be the most numerous Irish butterfly. The newly emerged Irish-born butterflies might not breed here. Irish-born butterflies may behave differently to their foreign-born parents. Their parents probably migrated shortly after they hatched from their pupae. The native Irish butterflies usually spend several days in a calm, settled state, feeding in flower-rich areas to develop fat reserves to prepare for migration southwards, not northwards. Suddenly, without any sign of restlessness in advance, the butterflies in an area will disappear.
How do Painted Lady butterflies head south in autumn?
The way the butterflies depart is interesting. In 2009 researchers at Rothamsted Research in the UK discovered that the Painted Lady returned south in autumn. The research also discovered, using radar, that the butterflies fly on average, at altitudes of about 500 metres when leaving us (some Painted Ladies may also travel northwards at altitude). This differs from the departure of their relative, the Red Admiral, which migrates at eye level. The altitude at which the Painted Lady butterflies depart from these islands is a key reason we believed that this cold-sensitive species simply died off in Ireland and Britain when cold weather arrived.
Expanding our understanding of the Painted Lady survival strategy
The view that the butterfly embarked on mass migration to Britain, Ireland and northern Europe followed by breeding and expiry of the population sounds like ecological suicide. This view appears a highly improbable outcome today. One interpretation of this behaviour before 2009 was that this migratory behaviour was a long-term strategy to survive inevitable climate change, in that somewhere a colony would be favourably located to replenish the population over time.
This hypothesis may still hold some relevance. The Red Admiral which also has no diapause in its life cycle (in other words, it has no diapause or ‘rest’ stage and reproduces continuously) is now breeding year-round in some milder coastal locations in these islands. The less hardy Painted Lady may breed here over the winter if the climate continues to warm. Indeed, Frank Smyth, who discovered Red Admiral breeding over the winter at Howth is monitoring the Painted Lady there to check if it breeds during our colder months. The young stages of the Painted Lady have not yet been found in Ireland over the winter months.
This is to speculate on changes that may occur. However, to focus on a change that has taken place: in my lifetime, the Painted Lady has never had four consecutive years of abundance (2016-2019) and has not arrived in large numbers in the dark, murky depths of an Irish January as it did this year. What else the butterfly has to teach us about our environment? We will have to wait and watch carefully…
What can you do to help?
The Painted Lady is not a fussy species. A habitat generalist, it occurs anywhere there are flowers. Waste ground (the early English lepidopterist and artist Moses Harris, a member of the Aurelians, the world’s first entomological society, produced a painting of the Painted Lady for a book The Aurelian published in 1766. The plate featured the butterfly and its immature stages on Spear Thistle growing amid broken pottery, clay pipe and glassware. The book cost about Stg £800 in today’s currency), gardens, parks, wood edges, mountains, sand dunes, bogs, fields will attract the butterfly.
All you need is flowers that produce nectar. Late in the year, allow ivy to flower. And to look after its breeding requirements you can plant or allow to grow any of these: Creeping Thistle, Spear Thistle, Marsh Thistle, Common Nettle, Common Malva (and other mallow species), Borage and Artichoke, among others. Grow these in an unshaded area.
As a butterfly-friendly gardener, you will have the satisfaction of seeing the butterfly and contributing to international conservation. Indeed, in 2009 it was calculated that millions more Painted Ladies departed these islands that autumn than had arrived that summer! If it breeds in your garden you will get the chance to study its development. The larva rarely moves far and you will have no trouble finding the larval tents, made by folding a leaf or leaves together with silk. The fully fed caterpillar usually leaves the plant to pupate but very occasionally it will pupate within the larval tent. The butterfly will most likely remain in your garden for a few days in autumn, feeding on your nectar before its amazing southbound journey. The southern parts of its European range, where some Painted Lady butterflies remain over the summer, will be cooler and the vegetation will have turned green again, making these areas suitable for the butterfly once more.
Finally, send us your records so we can track the butterfly over the coming weeks. For the details needed and how to send us your record, see https://butterflyconservation.ie/wp/records/