Our latest research shows that letting parts of your garden grow wild with long grass can increase butterfly numbers by up to 93%, so what better time to let your grass go wild than No Mow May! 

Experts at Plantlife explain more about the importance of long grass for wildlife and why you should get involved.

Imagine you’re a butterfly that’s flown into a garden. You may have flown across the English Channel to get here, or just woken up after sleeping through the cold winter. You may even have just developed wings, freshly transformed from a caterpillar into your new butterfly body.

You’re looking for food, shelter, a mate and maybe somewhere to lay your eggs. You fly over the carefully mown lawn but there’s nothing useful for you here, just lots of very short grass. But what’s that over in the corner? A patch of long grass, and some colourful looking flowers. Off you go to explore it.

No Mow May has encouraged thousands of gardeners to leave unmown patches like this. The recently published study by Butterfly Conservation shows just how beneficial this has been with significantly greater abundance and diversity of butterflies recorded in British gardens with long grass compared with those without.

So why are patches of unmown lawn so important for our butterflies, and indeed, many other types of insects?

Dr Abigail Lowe is an ecologist with the UK Centre for Ecology and Hydrology. Her recent scientific paper, published in Journal of Applied Ecology, on the feeding habits of pollinating insects shows what a great larder our native wildflowers provide in these unmown patches. By studying the pollen attached to the bodies of bumblebees, honeybees, solitary bees and hoverflies, she found that buttercups and Lesser Celandine were the most visited flowers in the Spring. Dandelions fed hoverflies and bumblebees but contributed more to the diet of honeybees and solitary bees.

In this study at the National Botanic Garden of Wales, Abigail observed that with over 5,000 different plant varieties to choose from across the Botanic Garden, the majority of plants visited by bees and hoverflies were native and near native to Britain. This may be because our insects have built up a relationship with our native wildflowers over thousands of years. They also find them easy to feed from. The flowers of buttercups and the Lesser Celandine are like an inviting dinner plate, with their nectar food in upstanding straws. The simple, open flowers of Dandelions are just as good. If you have a spare few minutes on a sunny day, just sit and watch how many pollinating insects come and feed from a Dandelion flower head.

For butterflies and moths, a bonus of unmown patches of lawn is the actual long grass itself. The Butterfly Conservation study showed that there was an 18% increase in butterfly numbers in gardens with long grass in highly urban areas. Why might this be?

Caterpillars! They need to eat plants to complete their life cycle into butterflies and moths.

Meadow Brown and Gatekeeper caterpillars prefer to feed on a range of fine grasses, so called because of their slim blades and thin stalks. With arching, narrow dark green leaves that thrives in shady lawns, a common fine leaved grass is the Red Fescue.

Cock’s-foot grass is a favourite foodplant of Large Skipper, Essex Skipper, Ringlet and Speckled Wood butterflies. This is a hip high grass, with big floppy leaves and a heavy looking flower head. It forms tussocks where moths can shelter over winter as caterpillars, and in spring, moths hide in the tussocks during the day and come up at night to feed. An increasingly popular hobby is to put out a moth trap at night – essentially a bright lightbulb that attracts moths. Try this in your garden and you might just get the likes of the Drinker moth, so called because of its caterpillar's habit of drinking drops of dew from grass stems.


Hordley, L.A. & Fox, R. (2024). Wildlife-friendly garden practices increase butterfly abundance and species richness in urban and arable landscapes. Science of The Total Environment, 929, 171503. https://doi.org/10.1016/j.scitotenv.2024.171503

Lowe, A., Jones, L., Brennan, G., Creer, S., & de Vere, N. (2022). Seasonal progression and differences in major floral resource use by bees and hoverflies in a diverse horticultural and agricultural landscape revealed by DNA metabarcoding. Journal of Applied Ecology, 59, 1484–1495. https://besjournals.onlinelibrary.wiley.com/doi/10.1111/1365-2664.14144