Gardening with butterflies in mind

Sarah Ronan, one of BBOWT’s volunteer butterfly surveyors, shares her two top tips for turning your garden into a butterfly haven.

Butterflies appear out of the blue from above, from the side, or even from below me – the latter perhaps a result of being disturbed by my clumsy footfall or my shadow – but every encounter is a delight. I feel fortunate to live in a world with these beautiful insects, flying about their short lives and finding me walking through mine or sitting in a garden with a cup of tea. Their fragility serves to remind me of mine.

After the worst year on record for butterflies in 2024, lepidopterologists (people who study butterflies) are very anxious about what this year will bring: a further decline? Will numbers stabilise or, more hopefully, increase? I am viewing each and every one of these precious creatures as a success story and something to celebrate, but what can we all do to help them?

 

Create a butterfly belt

A garden lawn with long grass for wildlife

A garden lawn with long grass for wildlife. Picture: Julian Weigall/ RHS

If you are a seasoned mower, please join me in creating a Butterfly Belt.

Many of us grew up with pristinely mown tramlines on our parents’ lawns and find it comforting to have similar on our own. My father said, ‘a tidy lawn is a tidy mind’, and proffered the sentiment in relation to his desk and our teenage bedrooms. However, recent research from hundreds of gardens proved that long grass increased butterfly numbers; significantly more butterflies, and a greater variety, were recorded in gardens where lawns were unmown because several species use long grass as a breeding habitat. Additionally, 31% more holly blue butterflies were recorded in gardens with flowering ivy.

I understand that it isn’t easy to hand your lawn over to nature – and it isn’t easy to mow it at the end of the summer either – but if you care about butterflies, moths, bees, and other insect life, please take a leap of faith this year, because it is doable and it will make a difference. No butterflies find any use for uniformly short, verdant green, daisy- and dandelion-free (in effect life-free), bowling green arrangements.

If letting go completely is a step too far, get experimental and mow a crop circle for garden furniture and mow paths to towards them, as well as towards greenhouses and sheds. This approach gives a feeling of structure. If you already have an unmown area, consider extending it and ask children or grandchildren to design a ‘Butterfly Belt’ sign to get them involved and explain to visitors what you’re doing.

 

Plant the caterpillars’ favourite foods

A group of small tortoiseshell caterpillars gathered on a nettle leaf

For the small tortoiseshell, whose numbers have dropped 86% since 1976, its sole food plant is nettles. Photo by Vaughn Matthews

A garden or meadow bursting with wild or cultivated plants, dripping with nectar and proffering a profusion of pollen, is excellent news for butterflies, bees, solitary wasps, hoverflies and whole host of other small flying beauties; it enables them to fuel their exertions, whirling around when it is warm and sunny, and provide for the next generation. Except for butterflies, this isn’t enough. An understanding of larval food – or ‘host’ – plants is critical. 

Many butterfly species will only lay their eggs on one particular plant, because their caterpillars eat its leaves exclusively. For the small tortoiseshell, whose numbers have dropped 86% since 1976, its sole food plant is nettles. Orange-tip females almost always lay eggs on garlic mustard or cuckoo flowers; for chalk hill blues, it’s horseshoe vetch; for the dark green fritillary, it’s violets. Clouded yellows lay eggs on clovers and trefoils; common blues almost always prefer bird’s-foot trefoil. For the small copper, it’s sorrel; for the purple emperor, it’s goat willow; for the comma, it’s nettle; for the red admiral, it’s nettle; for the peacock, it’s nettle. Silver-washed fritillaries prefer dog violet; small blues prefer kidney vetch, and I could go on. 

a tiny, orange rugby-ball-shaped egg embedded into a cuckooflower stem

The cuckooflower is a preferred food plant for the orange-tip caterpillar, and the butterfly lays its vibrant orange eggs on the stem.

Please consider your favourite butterfly and find a space in your garden to grow its larval food plant, or allow it to grow on your lawn, and you will make a difference.

You can see from the list above see how many species depend on nettles, so please don’t strim a patch you deem unsightly as there could just be, or are about to be, eggs or caterpillars of the increasingly scarce small tortoiseshell butterfly whose lives depend on those very nettles.

Find out more about caterpillar host plants