Moth and butterfly survival strategies

Blog post by The Wildlife Trusts on 23 Sep, 2021
When did you last see a caterpillar?

They're often cryptic creatures, with patterns that provide perfect camouflage as a piece of leaf, twig or bark. An unwary eye could pass right over one without even noticing it - which is exactly the point, as so many birds like to eat them. Many are also nocturnal, spending the day hiding in cracked bark, amongst grass, or even underground! Finding caterpillars can take a lot of luck or patient searching.

But some species become easier to spot as they reach their full size and wander in search of a place to pupate. Every August and September, The Wildlife Trusts are inundated with messages about elephant hawk-moth caterpillars, with people excitedly sharing their sightings or asking for help with identification. These chunky trunk-like caterpillars are searching for a sheltered spot on the ground, where they'll burrow into the soil or leaf litter and pupate, spending the winter within their cocoon. They won't emerge as adults until around the following May.

Many moths and butterflies spend the winter like this, tucked away in their pupal form, waiting to emerge in warmer weather, but some species spend the winter as eggs, including the rare black hairstreak. This beautiful butterfly is on the wing for a few short weeks around June, when females will lay eggs on blackthorn twigs. The larvae within will fully develop before winter arrives but won't emerge from their eggs until spring.

However, the most common way for moths and butterflies to spend the winter is as a caterpillar. They've adopted all sorts of survival strategies, with some species even continuing to feed throughout milder spells, though most enter a dormant state known as diapause (a little like hibernation in mammals) and don't feed again until spring. Some caterpillars enter diapause as soon as they hatch from their egg, others feed for a while and enter diapause when they're partly, or even fully, grown.

One species that spends the winter as a fully fed caterpillar is the fox moth. In early summer, young fox moth larvae are black with orange bands, but by September they've grown into huge hairy orange caterpillars. In late summer and early autumn they can often be seen on paths or low vegetation, before they secret themselves away in loose soil or leaf litter for the winter. In early spring, they'll emerge ready to pupate, and are often seen basking in the sunshine.

A few species buck the trend and overwinter as adults, sheltering from the worst of the weather in caves, tree cavities or even sheds and garages. These include the small tortoiseshell and peacock butterflies that occasionally try to hide away in houses, and the herald moths which huddle in groups on the walls of caves. A small number of hardy moths are actually active in the winter months, such as the winter moth and December moth - look out for them flying around outdoor lights on winter evenings.

Header image: Swallowtail caterpillar by Ian Saggers

Blog image credits: Elephant hawk-moth caterpillar by Lee Wright, black hairstreak by Philip Precey, fox moth caterpillar by Ian Saggers
Share this

Latest Blog Posts

Tips for birdwatching with your dog Tips for birdwatching with ...
by Izzy Williamson on 29 Jun, 2022
All’s welcome: celebrating LGBTQ+ pride at Norfolk Wildlife Trust All’s welcome: celebrating ...
by Meg Watts on 22 Jun, 2022
Celebrating our patron, Her Majesty The Queen, on her Platinum Jubilee Celebrating our patron, Her...
by Josie Collins on 01 Jun, 2022
Norfolk's Seals: Past, Present and Future Norfolk's Seals: Past, Pres...
by Katy Ellis on 19 May, 2022
Bishop’s Garden Wild project – how did it go? Bishop’s Garden Wild projec...
by Susannah Armstrong on 05 May, 2022
Put your garden to the test! Put your garden to the test!
by The Wildlife Trusts on 21 Apr, 2022
NWT Young People's Photography Competition - See the winners! NWT Young People's Photogra...
by Rachael Murray on 07 Apr, 2022
Getting Wild About Gardens Getting Wild About Gardens
by The Wildlife Trusts on 24 Mar, 2022
A tribute to Peter Lambley MBE, 1946-2022 A tribute to Peter Lambley ...
by Helen Baczkowska on 10 Mar, 2022
Wooing in the Wild Wooing in the Wild
by The Wildlife Trusts on 24 Feb, 2022
Mammal Mysteries Mammal Mysteries
by Darren Tansley on 10 Feb, 2022
A Conservation Work Party at Upton Fen A Conservation Work Party a...
by Jerry Simpson on 27 Jan, 2022
How to Identify Owls How to Identify Owls
by The Wildlife Trusts on 13 Jan, 2022
NWT Recommends: Holiday Reads NWT Recommends: Holiday Reads
by Emily Mildren & Susannah Armstrong (with contributions from several NWT staff!) on 17 Dec, 2021
Broadland Group's Return to Work at Upton Fen Broadland Group's Return to...
by Jerry Simpson on 09 Dec, 2021
The Queerness of Nature: In conversation with James McDermott The Queerness of Nature: In...
by Meg Watts & Molly Bernardin on 02 Dec, 2021
COP26: What's it all about and what do we want to achieve? COP26: What's it all about ...
by Kathryn Brown on 04 Nov, 2021
A New Direction: Starting Small by Creating Norfolk Wetlands A New Direction: Starting S...
by William Walker on 21 Oct, 2021
Broadland Group Moth Night Broadland Group Moth Night
by Jerry Simpson on 07 Oct, 2021
Out for Nature: Reflections on Pride with The Wildlife Trusts LGBTQ+ Employee Network Out for Nature: Reflections...
by Meg Watts on 14 Sep, 2021
Celebrating bees with our supporters, Lisa Angel Celebrating bees with our s...
by Susannah Armstrong & Lisa Angel on 09 Sep, 2021
Horsey Butterfly Walk by the Broadland Local Group Horsey Butterfly Walk by th...
by Jerry Simpson on 26 Aug, 2021
Recognising birds of prey Recognising birds of prey
by The Wildlife Trusts on 12 Aug, 2021
Cley Calling: Closer to Home Festival Review Cley Calling: Closer to Hom...
by Evie York on 29 Jul, 2021