Dig for butterflies
Britain’s butterflies are struggling. It’s more important than ever to do what we can to help.
BUTTERFLIES AND FLOWERS GO TOGETHER like jam and cream. Each is wonderful in its own right, but together they make something special. Watching butterflies flit around my mini meadow and tumble over the plants in my border makes my heart leap, and is one of the many rewards of gardening for wildlife. Seeing these pretty insects in our gardens is good for the soul – butterflies make us happy!
Sadly, these often-colourful pollinators are in serious decline. Results from the 2021 UK Butterfly Monitoring Scheme (UKBMS), led by Butterfly Conservation, the UK Centre for Ecology & Hydrology, the British Trust for Ornithology and the Joint Nature Conservation Committee, show that in terms of abundance, 2021 was a below-average year for UK butterflies, including many of our common and widespread species. The green-veined white, for instance, had its fourth worst year on record and the large skipper its fifth. The large white and small skipper both had difficult years, and the ringlet its lowest numbers since 2012.
Shorter animal surveys are also offering worrying snapshots In 2021, Butterfly Conservation’s Big Butterfly Count saw the overall number of butterflies recorded at its lowest level since the counts began in 2010, despite record numbers of people taking part (more than 150,000).
On average, participants clocked up just nine individual butterflies or moths per 15-minute count over the three-week survey, down from 11 in 2020. The peacock registered its lowest numbers since 2012; the small tortoiseshell had its third-worst summer since 2010.
“Some of the UK’s butterflies have more than one generation per year, meaning we would see adults in spring and summer. The majority of these double-brooded species experienced their worst year since the start of the Big Butterfly Count in 2010,” says senior surveys officer Zoë Randle. “Changes in the weather are likely to be the cause of this. March 2021 was warmer than average, which would have stimulated butterfly activity. May 2021 was very wet, however, which will have hampered feeding and breeding. These combined weather effects are likely to have reduced the spring generation, which has knock-on effects for the summer generation.”
Thankfully, there’s good news emerging among the bad. The UKBMS data also shows that some threatened species actually coped well in 2021. The brown hairstreak and silver-studded blue both had their best years since 1996, for instance, while the heath fritillary has increased by 112 per cent at monitored sites in the past decade. The Glanville fritillary, dingy skipper and chalk hill blue also had good years.
“When the general picture is of longterm decline, we’re delighted to see positive signs for some species,” says Richard Fox, Butterfly Conservation’s associate director of recording and monitoring. “These successes demonstrate what can be achieved through conservation efforts, and reinforces the importance of managing habitat to support butterflies. It is important, though, to remember that this data relates to abundance, not distribution. It’s good news, but it’s only one side of the story.”
We know only of the reasons why butterfly numbers are in decline. In the wider countryside, it’s thought that numbers are plummeting due to habitats being lost to the intensification of agriculture, changes in woodland management and so-called ‘urban creep’, where towns and cities expand into green spaces. But the problems don’t end there.
Back gardens are increasingly seen as ‘outdoor rooms’, with paving and decking replacing vegetation, and artificial lawns favoured over grass, while front gardens are surrendered to car parking. None of this is good for butterflies, which rely on plants and flowers – some of which need to be left intact for several months – to complete their life-cycles successfully.
Pesticide use is also a big problem, as is nitrogen run-off from agricultural fertilisers. This changes the chemical make-up of plants, causing them to grow bigger and, as a result, alters the microclimate that they provide to butterflies, by creating more shade, for instance. “More research is needed here,” says Fox, “but something’s going on.”
And all that is before we’ve even spoken about the increasing amounts of carbon dioxide in the atmosphere. “That’s another thing,” says Fox. “CO2 makes plants grow bigger, so again, research is needed to see if this could have an effect on microclimates and butterfly numbers.”
While CO2 may pose a threat to some butterflies, climate change is, conversely, offering opportunities for others. As temperatures rise, species such as the peacock, comma and speckled wood, previously found mainly in southern Britain, are spreading into northern England and Scotland. Yet concerns remain that extreme weather events – droughts, floods and storms – will put further pressure on populations and their delicate life-cycles, many of which rely on the perfect combination of British weather: sunshine and showers.
So what can we do to help our butterflies and moths? Well, plenty. We have 22 million gardens in the UK and many more balconies, roof gardens, allotments and windowsills besides. By clothing these spaces with the right plants, we can give them a fighting chance. Spring is the ideal time to start planting and the more plants we can grow for butterflies, the better their odds this year and into the future.
The first thing to do is provide a source of nectar Most species rely on this sugary fluid to give them the energy they need to fly and find a mate. By having flowers in bloom consistently from March to November, you can provide a nectar bar for most of the year. It might be primroses, bluebells and forget-me-nots in spring; alliums, lavender and scabious in summer; then late-flowering Verbena bonariensis, sedums and rudbeckias in autumn (see planting guide below). It’s also important to remember that some species, such as the speckled wood, drink honeydew, a sweet substance secreted by aphids. So simply by being kinder to aphids and not eradicating them from your garden, you can help butterflies to survive.
As well as providing nectar, it’s also vital to consider butterfly caterpillars. To reproduce, butterflies lay eggs and will only do so on specific foodplants. By nurturing more of these in our gardens and allotments, we can offer breeding opportunities that otherwise wouldn’t exist. Choose cuckooflower and garlic mustard for caterpillars of the orange-tip butterfly, hops for the comma, and holly and ivy for the holly blue. A large patch of nettles in sunshine is what’s needed for caterpillars of the peacock, red admiral and small tortoiseshell, while long grassy areas provide breeding opportunities for the speckled wood, gatekeeper, ringlet and meadow brown (see foodplant guide below).
Don’t forget that caterpillars support other wildlife, such as birds, hedgehogs and toads, adding to the overall wildlife value of your garden.
Butterflies also need places to shelter and hibernate Five UK species (brimstone, comma, peacock, small tortoiseshell and red admiral) overwinter as adults, and retreat among log piles and vegetation for the winter, while the orange-tip overwinters as a chrysalis, usually on the old stems of its caterpillar foodplant. The speckled wood may overwinter as a caterpillar or chrysalis, usually in thickets of grass or beneath leaf litter. This makes them vulnerable to tidy gardeners, who may cut back ivy, trim long grass or clear away ‘spent plants’, not realising that they’re still being used by wildlife. Leave plants intact over winter and clear them in spring instead, but always check for chrysalises just in case.
Butterfly-friendly gardens and outdoor spaces not only provide breeding and feeding opportunities, but they look nicer too. Who doesn’t love a garden packed with colourful, scented blooms such as lavender and viper’s bugloss? Who wants to look at a bare fence when you can swathe it with ivy or hops and provide homes for butterflies in the process? Why opt for a cropped, lifeless lawn when you can let patches grow long and shelter caterpillars? Garden ponds are wonderful things, but take them a step further and plant the edges with primroses, cowslips and cuckooflowers to help orange-tips thrive.
If you don’t have a garden, you can still contribute to the cause with pots, window boxes and hanging baskets. You may not host breeding butterflies, but you’ll establish a refuelling post for any individuals searching for a mate or somewhere else to lay their eggs. Herbs such as lavender, oregano, chives and hyssop are perfect for pots as they’re drought-tolerant, so won’t need watering as often as thirstier plants. There’s also a range of butterfly-friendly blooms for hanging baskets and windowboxes, including bird’sfoot trefoil, nasturtiums and the wonderfully named poached egg plant.
In my garden and allotment, butterfly numbers could be higher I live in an urban area and have seen significant declines in peacocks and small tortoiseshells over the past five years, but that doesn’t stop me trying to help them. As well as an almost year-round supply of nectar and aphid honeydew, I have a large patch of nettles in full sun, lots of long grass and other caterpillar food plants such as hops, holly, ivy and buckthorn. Around my pond, I’ve grown cuckooflower for the orange-tips. I’ve yet to spot one in my garden, but I refuse to give up. I leave plants uncut in autumn, lest any chrysalises remain on the stems (I often find red admiral caterpillars on nettles as late as December), and I don’t use any bug sprays, fungicides or artificial plant foods, to maintain the most natural habitat possible.
No matter how small they might be, our gardens and outside spaces can provide food and shelter for butterflies. Balconies and windowsills can serve as stepping stones while larger spaces can offer more complete habitats, including caterpillar foodplants, basking spots, overwintering sites and nectar.
Whatever your space, clothe it in plants and let your grass grow long. These may seem like small steps, but they could be a lifeline to our precious butterflies, which really, really, need our help.
COUNT FOR BUTTERFLIES
Help surveying efforts by joining this year’s Big Butterfly Count, which takes place from 15th July to 7th August. You can also log ongoing sightings at gardenbutterflysurvey.org.
Other ways to help butterflies
Leave windfall fruit in autumn
Apples and pears left on the ground provide an important sweet treat for butterflies in autumn, as they look for alternatives to nectar, which is in short supply.
Create basking spots
Placing large stones in a sunny border or making a rock garden can provide the perfect environment for butterflies to bask and stay warm.
Create muddy spots for ‘puddling’
Some butterflies, particularly blues, feed on the salts and minerals in mud. The mud around your pond or in well-watered spots in the garden are perfect for them.
ABOUT THE AUTHOR
Kate is an award-winning author and journalist specialising in wildlife gardening.
She edits the wildlife pages of BBC Gardeners’ World magazine and her latest book is How to Create a Wildlife Pond (DK, £14.99)
Seasonal plants to provide
NECTAR FOR BUTTERFLIES
SPRING
Cuckooflower
Cardamine pratensis
Flowering from April to May, this is a pretty, moisture-loving perennial with lilac blooms. It is also a caterpillar foodplant.
Attracts: orange-tip and greenveined white
English bluebell
Hyacinthoides non-scripta
Flowering from April to May, English bluebell has drooped stems of lilac flowers and a delicate fragrance.
Attracts: brimstone and orange-tip
Primrose
Primula vulgaris
An early source of nectar, flowering from March. It’s also a larval foodplant of the Duke of Burgundy butterfly.
Attracts: brimstone, small tortoiseshell and peacock
Dandelion
Taraxacum officinale
Often regarded as a weed, but as it flowers from March to autumn it is a good early source of nectar when little else is in flower.
Attracts: brimstone, orange-tip and small tortoiseshell
SUMMER
Buddleia
Buddleja davidii
Flowers from mid to late summer. If you cut it back hard in May, it will bloom later, providing nectar when other plants have finished.
Attracts: small tortoiseshell, peacock, painted lady and more!
Marjoram
Origanum majorana
Also known as oregano, its leaves are edible, but if you avoid cutting it, it will flower and become a magnet for butterflies.
Attracts: gatekeeper, large skipper and small tortoiseshell
Lavender
Lavandula spp.
Use to edge beds or paths, and in pots. The Lavandula x intermedia hybrids grow larger and will provide more nectar.
Attracts: small white, large white, small tortoiseshell and red
Greater knapweed
Centaurea scabiosa
A key species of perennial meadows, greater knapweed flowers from midsummer. Some moths use it as a larval foodplant.
Attracts: common blue, marbled white and small tortoiseshell
AUTUMN
Purple top
Verbena bonariensis
Flowers from late summer to mid-autumn. Grow at the back of a sunny border or the smaller variety ‘Lollipop’ can be potted.
Attracts: small tortoiseshell, painted lady and red admiral
Coneflower
Echinacea purpurea
This North American native thrives in well-drained soil in a sheltered, sunny spot. Deadhead spent blooms to prolong flowering.
Attracts: small tortoiseshell, painted lady and red admiral
Ice plant
Hylotelephium spectabile
Flowering from August to October, this succulent is drought-tolerant. Cut back in May (‘Chelsea Chop’) to encourage later blooming.
Attracts: small tortoiseshell, painted lady and speckled wood
Perennial wallflower
Erysimum spp.
In southern regions, perennial wallflower can bloom throughout the year. Flowers are sterile, so produce only nectar, not pollen.
Attracts: large white, small white, small tortoiseshell, large skipper
Top species to provide
FOODPLANTS FOR CATEPILLARS
Nettle
Urtica spp.
Grow in as large a clump as you have space for, in full sun, and look out for large ‘tents’ of caterpillars, or a single larva in a rolled-up leaf.
Attracts: small tortoiseshell, red admiral, peacock, painted lady and comma
Buckthorn
Frangula alnus and Rhamnus cathartica
Both alder and purging buckthorns are foodplants for the brimstone. Plant in sunshine, as a specimen shrub or as part of a mixed native hedge. Avoid any pruning until autumn.
Attracts: brimstone
Cuckooflower
Cardamine pratensis
In addition to providing nectar, this species is also a caterpillar foodplant. Orange-tips overwinter as pupae on the old stems and emerge the following spring.
Attracts: orange-tip and green-veined white
Long grasses
bents (Agrostis), couch (Elytrigia), fescues (Festuca)
Avoid cutting until late summer to benefit grass-feeding species. If you can leave some areas completely uncut, you will benefit the overwintering species too.
Attracts: gatekeeper, meadow brown and speckled wood
Holly
Ilex spp.
The high-flying holly blue butterfly feeds on the flower buds, berries and terminal leaves of holly in spring, and ivy in summer. Grow as a shrub, small tree or as part of a hedge. They are not fussy plants and need minimal pruning.
Attracts: holly blue
Hop
Humulus lupulus
Grow this perennial climber against a fence or wall, or up a trellis, and cut back in autumn. Comma used to be a pest of hops but switched to nettles when the hop industry declined. It’s still loved as a larval foodplant though.
Attracts: comma
Nasturtium
Tropaeolum spp.
Cabbage whites typically feed on brassicas and are the bane of veg growers’ lives. But they also use nasturtium – plant it next to brassicas so you can move caterpillars from them to this sacrificial plant.
Attracts: large and small whites
Bird’s-foot trefoil
Lotus corniculatus
If you have a meadow, you could try attracting the common blue butterfly, which is found in grassland habitats. Bird’s-foot trefoil is its main foodplant – grow among the long grass or at the front of a border.
Attracts: common blue
Garlic mustard
Alliaria petiolata
Grows well in shady spots and its leaves have a faint whiff of garlic. Remember that orange-tips overwinter as pupae on the old stems, so avoid cutting back spent plants.
Attracts: orange-tip and green-veined white
Ivy
Hedera helix
Plant in sun or shade, against a fence or wall. Ivy has a reputation for destroying buildings but only those with existing holes, which the plant’s roots exploit. Holly blue lays eggs singly at the base of the flower buds in summer.
Attracts: holly blue
Ragwort
Senecio jacobaea
Don’t forget moth caterpillars – the cinnabar is a striking, red-and-black day-flying species. Ragwort can be harmful to livestock, such as horses and cattle, but doesn’t usually create issues in gardens. Stems can reach up to 1.5m high.
Attracts: cinnabar moth
Lady’s bedstraw
Galium verum
Foodplant for another day-flying species (and a superb one) – the hummingbird hawkmoth, which also feeds on hedge bedstraw and wild madder. Lady’s bedstraw erupts with richly scented flowers in July and August.
Attracts: hummingbird hawkmoth