Conserving our butterflies and caterpillars at home

14 October 2020
Comments 2
Category Blog, News, Wild Christian
14 October 2020, Comments 2

During lockdown, spending time in my small garden was an essential part of my daily routine. I valued the time to slow down and really appreciate creation as flowers opened, birds fed their young and butterflies flitted around the early blossom. The wildlife I enjoyed watching has inspired me to continue taking time over autumn and winter to ensure my garden continues to provide food and shelter for all that I saw, including butterflies.

There are only 59 species of butterfly in the UK1, but what do they do in winter, and where do they go? Each butterfly species tackles the problems of a long, cold, wet, winter differently, so it can be tricky to ensure all requirements are met. Butterflies face new issues in a changing climate, with milder, stormier and damper winters, making it an equally challenging time for adult butterflies emerging to find that their main food plants have already flowered or have not yet started to flower.

The most common way for butterflies to survive winter is as caterpillars, with thirty-one species choosing this strategy1. As vegetation dies off in autumn, the caterpillars will find a dry pile of leaves to hide under for the winter. It may seem like a long way to crawl to find a safe hiding place, but with over 4000 muscles, compared to our 629, they are quite capable of hunting out the safest of overwintering spaces4.

Despite their delicate appearance, five British butterfly species survive the winter as adults. Peacock and red admiral butterflies, for example, shelter inside the roofs of cool garages or sheds in winter, and brimstone butterflies shelter in thick vegetation such as ivy. 

Adult brimstones awaken as the weather warms up ready to fill up on dandelion, knapweed, cowslip and bluebell nectar before laying their eggs. These hatched eggs can be spotted on buckthorn and alder buckthorn shrubs2 as indistinct, green caterpillars between May and mid-June. Ensuring a good supply of bluebell and teasel for the adults emerging in August, plus dense areas of buckthorn scrub for caterpillar food and ivy for adult winter shelter, will help this vivid yellow butterfly continue to be a delightful early spring sighting. 

Eleven butterfly species spend their winter as pupae1 including the Larger white. From experience, you can avoid your vegetable patch crops being entirely eaten by leaving the stalk and leaves behind of the harvested cauliflower and cabbages and relocating any caterpillars from your broccoli. This way you can still have your crop and eat it, whilst ensuring the garden is full of butterflies next year! These caterpillars have mostly pupated by September and will overwinter as such, hanging from sheds, fences or walls, safe in the knowledge that the accumulation of cabbage compounds will make them unpalatable to many potential predators.

A picture containing outdoor, pink, purple, tree

Description automatically generated

Although not every caterpillar turns into a butterfly (many turn into moths), all are an important part of the diversity of creation. Sadly, butterflies are in decline. The Butterfly Conservation Trusts report a 76% drop in abundance or occurrence since 19765,6. Planting butterfly-friendly nectar plants in our gardens may be helping as recent trends show this decline is slowing. With careful planning, and a willingness to sacrifice some traditional garden aesthetics, we can help protect the whole life-cycle of the butterfly and ensure that butterflies will continue to enchant us with their beauty each year.

How can you help?

Plant It: The Woodland Trust9 has some helpful guides on species associated with woodlands, with a list of adult and young food plants to consider planting in your garden to encourage specific butterflies. For example, stinging nettle isn’t an obvious garden plant, but it’s a key food plant for caterpillars of small tortoiseshell, red admiral, peacock, comma and painted lady. If you can, set aside an area to be left wild to nettles, or encourage your local council to leave a section of the park for nettles so these butterflies have plenty of food for their caterpillars.

A close up of a flower

Description automatically generated

Leave It: With so many butterflies surviving the winter as caterpillars and pupa1, garden-tidying risks halting the life cycle. Leave sections of garden wild over winter, and if you must tidy, try to do so carefully, relocating any caterpillars or pupa that you find. Be careful and use gloves, as some caterpillars have irritant hairs. These yet-to-be butterflies can also provide food for other garden favourites such as hedgehog and birds during the winter when food is scarce, so it is well worth leaving some unmanaged areas of your garden for wildlife… and it means less work for you!

Record It: The Butterfly Conservation website2 can help you identify butterflies you’ve seen. You can join in next July with The Big Butterfly Count7 or submit records now on the iRecord app8

About the Author: Dr Rosalind King has had a life-long interest in all things wild. Her early days were spent observing caterpillars in her English and South African garden, which led to an Ecology degree from Lancaster University and a Ph.D. in Restoration Ecology from Liverpool University. Based in North West England, she actively manages her garden for wildlife, undertakes conservation activities in her local woods and enjoys a varied career as a Consultant Ecologist helping bats, badgers, newts and other creatures stay safe.

References

1.  UK Butterflies https://www.ukbutterflies.co.uk/species_phenologies.php

2. Butterfly Conservation https://butterfly-conservation.org/uk-butterflies/a-to-z

4. World Atlas https://www.worldatlas.com/articles/10-interesting-facts-about-caterpillars.html

5. United Kingdom Butterfly Monitoring Scheme https://www.ukbms.org/

6. Butterfly Conservation https://butterfly-conservation.org/butterflies/the-state-of-britains-butterflies

7. The Big Butterfly Count  https://bigbutterflycount.butterfly-conservation.org

8. Biological Records Centre https://www.brc.ac.uk/irecord/

9. Woodland Trust  https://www.woodlandtrust.org.uk/trees-woods-and-wildlife/animals/butterflies

2 responses on “Conserving our butterflies and caterpillars at home

  1. Elaine Roff says:

    Thanks for very informative article. Just a query what should you do if a hibernating butterfly wakes up too early ? We had one couple of years ago iinour loft.

  2. Rosalind King says:

    Hi Elaine,

    This happens often with some butterflies trying to find cool places to rest over winter (Peacock butterflies especially). They go into houses, then the heating comes on and they wake up too early. If you can catch them in a box and release them into a place which will stay cool and dry all winter (such as a shed or garage) then this would be the best option as they will soon settle back to sleep in a safe place. Maybe leave them in the box for an hour or so to cool down in the garage / shed, then gently transfer them to a safe space in the building. Greenhouses will get too hot on sunny days, so best not to relocate the butterflies there. More tips can be found here: https://nurturing-nature.co.uk/gardening-for-wildlife/what-to-do-with-hibernating-butterflies-in-your-house/
    Hope this helps for next time you discover unexpected butterflies in your house:-)
    Cheers
    Rosalind

Leave a Reply

Your email address will not be published. Required fields are marked *