The flight time from Marrakech to London is about three and a half hours. This is a direct flight at a speed of about five hundred miles per hour. The journey for a butterfly born in the Atlas Mountains of Morocco flying north towards the UK is significantly less direct and far more impressive.
Painted Lady butterflies are a well known site in Britain but unlike most of our normal butterflies they do not survive our winter in any form (e.g. egg, caterpillar, pupa or adult butterfly). Their regular presence in our landscapes and gardens in summer is due to the fact that they are strong migrants, flying across two seas and a distance of well over 1500 miles.
Given suitable conditions in the Atlas Mountains, many hundreds of thousands of Painted Lady butterflies can be born in spring, and when the winds are favourable, many migrate north on a journey that takes them across the Mediterranean through Portugal, Spain and France. Some could reach southern England in March, but more will arrive in April, May and June.
Some butterflies will not make it to the UK, they might stop on the way to breed, but because their offspring can be produced fairly quickly, the next generation continues the northward journey started by their parents, who came with us in the summer arrived.
One thing is for sure. Painted Lady butterflies are always seen in the UK in summer and in a good year we can witness an invasion in large numbers across the country. The most recent major invasions happened in 2019 and 2009, before that it was 1996, but these events happened regularly over a long period of time; Records of similar invasions in 1879 and 1903 confirm this.
Given the effort it takes to get here, I can only assume that Painted Lady butterflies are bound to enjoy the British summer. When they arrive their first task will be to feed on nectar from flowers in our gardens, hedges and meadows. Next they need to breed. It is important in this process to find the right plants for their caterpillars to feed on.
Spear thistle is the most commonly used food plant for Painted Lady.
Painted Lady Food Plants
Thistles are very fond of thistles, especially the creeping thistle, also known as the common thistle, Cirsium vulgare. Their choice of food plant is reflected in the butterfly’s scientific name, Vanessa carduifor thistles belong either to the inflorescence or zircium family depending on the shape of their seed heads.
As gardeners, we can help by allowing a piece of our garden to naturalize and welcoming the growth of thistles in a sunny, sheltered spot. Our reward is to see Painted Lady laying eggs and watching their caterpillars develop.
The painted lady caterpillar forms a protective web around itself where it eats.
Caterpillars and Life Cycle
Painted Lady caterpillars form protective webs around themselves to prevent birds from eating them. Inside the web, the black spiny caterpillar eats the leaf, and as it grows, the small webs become larger tents, sometimes spanning multiple leaves. Their webs become increasingly noticeable as they fill with the caterpillar’s own droppings before the caterpillar eventually pupates. The whole process from egg to adult butterfly is quite short, maybe between thirty and forty days.
Because of this quick turnaround, we usually see a fresh generation of lively new Painted Lady butterflies in the summer. It is not uncommon to find them feeding on buddleia in gardens alongside other large butterflies such as peacocks and small tortoiseshells. But the next few months will be very different for these species.
Peacock butterfly and Tortoiseshell will survive our winter in their adult forms, giving them an easy start next year, but painted ladies cannot do this. Instead, this brave new generation of Painted Lady butterflies must begin a southern migration.
The return journey
In a superficial way, this journey could be compared to the migration of birds like swallows and house martins, but in a very significant way it is very different. The butterflies making this return migration are not the same butterflies that arrived in spring. They might be a generation or two later. It’s amazing that butterflies can make such long journeys, and it never ceases to amaze me that individual butterflies know which way to fly.
Some of the British born people might make it as far as Morocco, others might stop along the way. Any left behind in the UK will likely die without a chance to lay eggs of their own. Maybe Painted Lady butterflies will winter here one day and their life will be a little easier, but for now let’s revel in this persistent wonder of migration.
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