Naturehood: Transform your garden into a butterfly paradise
Some species of butterflies, including the small tortoiseshell, hibernate as adults.
You may spot one over winter in your garden shed, and the sight of them emerging in spring from their long sleep is wonderful, but sadly, these creatures are becoming less common. Once abundant, the UK’s small tortoiseshell butterfly has experienced a population decline of three quarters since the 1970s. Their numbers now vary dramatically year on year due to changes in climate, habitat loss and fragmentation. The long hot summer that we all enjoyed in 2019 is expected to send their numbers plummeting this year because of its effect on their reproduction cycle.
With 97% fewer wildflower meadows now than in the 1940s, and intensive farming practices removing lots of hedgerow habitat, it’s easy to see why these colourful invertebrates need our help.
With a few simple actions your garden you can help to provide more habitat for the small tortoiseshell butterfly, plus a number of other pollinator species, so that once again they will be a common sight when you relax in the garden on a sunny summer’s day.
The small tortoiseshell butterfly
The small tortoiseshell butterfly (Algais urticae) is a medium-sized butterfly, and has striking black and orange patterns, with blue crescents along the wing edges. These butterflies overwinter as adults, in sites like garden sheds, so may be seen all year round, if conditions allow. They will usually emerge from hibernation at the end of March or beginning of April, but this can vary from the south to the north of the UK. They are most active during sunny weather above 14°C.
During the summer they may have two or three broods, laying batches of between 80-100 eggs on sheltered nettle plants that are in direct sunlight. These eggs hatch into caterpillars, which feed on the nettle plants as they grow, and then form a chrysalis before the adult butterfly emerges.
Why are they in decline?
Butterflies, and other pollinators such as bees, have been affected by habitat loss and farming intensification, pesticides, disease and climate change, and in the case of the small tortoiseshell butterfly, an invasive parasitic fly called Sturmia bella. This fly lays its eggs on the foodplant of the butterfly, the butterfly larvae eat the eggs, and the eggs develop within the larvae, eventually emerging and killing the larvae. There are many factors involved in butterfly decline, but, given the right resources, we can help them to flourish.
It’s not about the size of your garden, it’s about how you use it.
Small tortoiseshell butterflies can be found in a huge variety of habitats, from urban rooftop gardens to countryside hedgerows and high up in sunny mountain meadows. Gardens, whether urban, sub-urban or rural, can be improved in a few simple steps to provide fantastic habitat for these, and many other pollinators too.
A tiny garden, full of nectar-rich plants will provide a wealth of food for pollinators. Including a variety of flower structures (flat, bell-shaped, tubular) will appeal to a diverse range of insects, as well as making your flower borders look more interesting. If you have a patio garden, get creative with pots and planters! Planting flowers in sunny areas is also a fantastic idea. Butterflies are active from spring through to autumn, so as you turn your thoughts to the spring planting season, make sure to include plants that flower in different seasons. Providing autumn nectar will help some species of butterfly fatten up for winter hibernation, or long migrations to warmer locations. For more information on what you can do, take a look at the plants for pollinators advice on the Naturehood website.
Many gardens have grass that is mown short with enthusiasm, and although this may look tidy, it’s not great for wildlife. To make your lawn look more interesting, and importantly, more biodiverse, set aside some areas to grow longer. To make these areas look deliberate, mow paths through them. You may be surprised at the flowers that appear, and if you want more colour you could think about actively planting a flower rich lawn too.
The use of pesticides on farmland to reduce crop pests can have a devastating effect not only on the target species, but many other invertebrates too. Choosing not to use pesticides in your garden reduces the concoction of chemicals that pollinators are exposed to, and there are some interesting alternatives you could try. By planting strongly-scented plants such as marigolds, sage and lavender near your vegetables or flowers, you can deter some insects that are sometimes classed as pests.
Gardens provide stepping stones between larger areas of habitat, creating corridors so that animals can move across the landscape. Linking up local nature reserves, parks and other gardens will help pollinator populations become more resilient, provide more food, and enable them to access more suitable habitat in which to reproduce – a key factor in the success of any species. For the small tortoiseshell, nettles are key. If you’re thinking of tidying that patch of nettles at the bottom of the garden – think twice, could you leave them so that butterflies can lay their eggs?
Naturehood aims to bring communities together to act positively for wildlife. We encourage individuals to think about their gardens and green spaces as areas where both people and wildlife can thrive, and implement wildlife-friendly actions to boost biodiversity. Signing up to Naturehood is free, and helps our scientists with research into the use of urban gardens for wildlife.
By Chloë Dalglish – Naturehood Community Engagement Officer Oxford, Earthwatch Europe
First published by BBC Springwatch, January 2020