Welcome to peak butterfly season

RSPB’s Morwenna Alldis is all of a flutter this month as she goes on a fact-finding mission about our UK butterflies

Mother Nature treats us to a visual feast at this time of year, as flowers paint our borders and butterflies flit bursts of colour across blue skies, enjoying all those nectar-rich flowers you’ve grown.

Photo above: Orange tip butterfly resting on vegetation by Ben Andrew (rspb-images.com)

The UK is home to 59 species of butterfly – the painted lady and the clouded yellow are migrants to the UK each year.

Butterflies are important markers for the health of our environment – where butterflies and moths flourish, you’ll also find a lot of invertebrates. And these three species are also vital pollinators for our plants, natural pest controllers, and food sources for birds and bats. Fun fact from Butterfly Conservation - blue tits eat around 50 billion moth caterpillars each year in Britain and Ireland!

Photo: Blue tit with caterpillar in beak to feed young by Matt Wilkinson (rspb-images.com)

In celebration of these colourful signs of summer, we’ve answered Google’s most searched for butterfly questions:

Do all caterpillars turn into butterflies?

No – caterpillars will turn into either a butterfly or a moth and there’s no foolproof way of telling beforehand which winged beauty a caterpillar will become. But all caterpillars will undergo a metamorphosis.

Photo above: Caterpillar of a large white butterfly on a leaf by Jenny Tweedie (rspb-images.com)

Do butterflies have hearts?

Yes, like all insects butterflies have a heart of sorts. It is a long chambered heart that runs the length of its upper body and pumps its blood or hemolymph from the rear of their bodies, forward to their internal organs. Butterflies have an open circulatory system (ours is closed), whereby their blood flows freely around their bodies.

Recent studies by Harvard and Columbia, using infrared mapping technology to study butterfly wings, have discovered that butterflies have hearts in their wings. Previously thought to be made up of lifeless cells, wings are now known to be a network of intricate living cells that help to regulate the butterfly’s temperature, with a wing heart that beats a few times a minute to manage blood flow. Butterflies are extremely sensitive to temperature. They are cold blooded and prefer warm climates.

Photo above: Red admiral butterfly feeding on flower by Jenny Tweedie (rspb-images.com)

Why are butterflies called ‘butterflies’?

My favourite explanations are:

• The “Anglo-Saxons called them 'butterfloege' because their most common butterfly was the yellow brimstone.
• The folklore that at night witches transformed into winged creatures that stole butter!

Can butterflies taste with their feet?

Yes – they have taste sensors in their feet so that when they land on a leaf they can taste it. This allows them to check if their caterpillars can eat it before they lay their eggs.

Photo above: Red admiral butterfly feeding on ivy by Mark Gurney (rspb-images.com)

How long do butterflies live?

Sadly, most beautiful butterflies only live for 2-4 weeks. However, the oldest butterfly recorded was a brimstone that lived for 9-12 months.

Where do butterflies live?

Different species of butterflies need different homes, depending on factors such as the plants which their caterpillars feed upon and the nectar giving flowers that adult butterflies use as a food source. Whilst some butterflies are flexible and will happily alight on different flowers in your back garden – others have very specific needs and so any changes to their homes, including climate change, can have a massive impact on the health of that species.

We have lost five species of butterflies over the last 150 years and 76% of UK butterflies are in decline.

RSPB nature reserves provide vital homes for butterflies and we have enhanced some features of our reserves to meet the specific needs of some of the UK’s rarer species, here are two examples:

RSPB Winterbourne Downs, Wiltshire

• Created two large s-shaped chalk banks, planted with food for chalk grassland butterflies, including kidney vetch for the caterpillars of the small blue butterfly
• Planted several hundred metres of hedgerows with blackthorn. The rare brown hairstreak butterfly lays its eggs on the twigs
• Planted disease-resistant elm trees. The loss of elms across the UK has had a big impact on populations of white-letter hairstreak butterflies which use the trees for breeding
• Created scrub and grassland areas to attract the rare Duke of Burgundy butterfly

Photo above: Volunteers sowing wildflower seeds on Butterfly Bank at RSPB Winterbourne Downs.  

Photo above: Small blue butterfly and kidney vetch flower on chalk bank at RSPB Winterbourne Downs by Patrick Cashman (rspb-images.com)

Photo above: Brown hairstreak butterfly resting on a leaf. Both photos by Patrick Cashman

RSPB Blean Woods, Kent

• One of the last remaining strongholds of the threatened heath fritillary butterfly
• Created sunny, warm, and sheltered areas across the reserve and encouraged the growth of the insect’s food plant, a dainty yellow flower called cow-wheat
• The reserve reached a peak count of 2200 heath fritillaries in 2020

Photo above: Heath fritillary by Jackie Cooper (rspb-images.com)

How can we help our butterflies?

Nature reserves are just part of the solution to helping our butterflies thrive. Our gardens provide essential homes and food sources too – so each of us can help by:

• Planting nectar rich flowers during the summer months. Your garden butterflies will most enjoy: buddleia (but avoid Buddleia davidii as it can be highly invasive), verbena bonariensis, lavender, perennial wallflower, and marjoram. Find our full butterfly planting guide, here
• Plant food for caterpillars. A nettle patch is ideal for red admirals, commas, and small tortoiseshells
• Place large stones in sunny spots around your garden or leave sunny patches of wall bare so butterflies can bask
• Grow climbing plants for shelter from wet and frosty weather for butterflies and moths.
• Create a little log pile – it’s the perfect hibernation spot for butterflies and moths
• Pick up our butterfly attractor native wildflower seeds here and a handy butterfly ID guide here – so you can get to know the butterflies that enjoy your garden feast.

Photo above: Small tortoiseshell butterfly on flowers by Jenny Tweedie (rspb-images.com)

If you want to make an even bigger difference, consider joining the RSPB – your membership donation supports the work we do to boost populations of threatened butterflies.