The United Kingdom is currently experiencing a notable surge in Painted Lady butterflies, leading to what some naturalists are dubbing a 'Painted Lady Summer'. These distinctive orange, black-tipped, and white-spotted insects are being observed in unprecedented numbers across various regions, much earlier in the year than typically expected.
The arrival of these migratory butterflies is often compared to the anticipation of the first swallow. While initial reports emerged from Wales and Cumbria in mid-April, widespread sightings across areas such as Weardale only became common by mid-May. Experts suggest that some of the earliest arrivals may undertake a direct journey from Morocco, aided by southerly winds, though the majority arrive in successive waves, breeding in France and Spain before continuing their northward journey.
The Painted Lady's short life cycle, transforming from egg to adult in approximately six weeks, allows their population to multiply rapidly as they advance northwards. This creates a continuous, expanding wave of butterflies that reaches British shores from midsummer onwards. Such spectacular migrations are considered legendary among lepidopterists, with previous significant events recalled in 1996, when hundreds were seen along the coast near Whitby and as far north as Orkney and Shetland, and more recently in 2009. The scale and frequency of these events are heavily influenced by favourable winds and mild weather conditions.
The future of these recent arrivals is intriguing. They have sufficient time to produce two further generations, whose caterpillars will feed on thistles, before the onset of autumn frosts. Historically, it was believed that these butterflies would perish during the UK's colder, wetter winters. However, a significant discovery in 2012 revealed that Painted Ladies undertake a reverse migration, flying back towards Africa at high altitudes beyond ground observation.
An additional consideration is the potential impact of a warming climate. There is speculation among experts that milder winters in England's southern counties could eventually allow some Painted Ladies to overwinter in the UK, altering their traditional migratory patterns. However, the allure and mystique of the Painted Lady largely stem from their epic journey originating in Morocco, a 'frisson of anticipation' that might diminish if their journey began closer to home.
Source: Phil Gates