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Winter Homes for Insects 

Published in a November  issue of Organic Gardening Magazine

As winter approaches do you look forward to the first glimpse of a brimstone butterfly or anticipate the friendly drone of a queen bumblebee in the spring?  If you do, and which gardener doesn’t, then this is the time to make sure that the insects and other invertebrates that have chosen to reside in your garden have somewhere safe to spend the winter.  Many of the smaller garden creepy crawlies don’t make it through the colder weather, indeed many invertebrates have life cycles that mean the majority of that particular species are not designed to see another spring.  Honey bee numbers in a hive for example, reduce naturally to a small nucleus of individuals; enough bees to begin a new colony in the spring, but a small enough number to survive on existing honey supplies until nectar and pollen are available again.  Many caterpillars and moths spend the winter as pupae in a protective cocoon or hard shelled chrysalis, and other insects reduce their bodily functions to a basic minimum level and hibernate the winter cold away.  The winter months can be difficult for all our native wildlife but there are many positive steps we can, and should, take as gardeners to ensure we start the new growing year with a good complement of useful, beneficial creatures around us.

Anyone who has ever placed a garden cane in the ground knows that insects are ready and willing to find their own shelter.  If in late summer you stake dahlias or gladioli as I sometimes do you, will do doubt know how readily earwigs find their way into the naturally hollow centres of bamboo canes.  An overturned stone may reveal a clutch of wood lice or a stack of clay pots contain snails tucked up ready for the winter.  Some of these creatures gardeners may feel better off without, but these winter hiding places can give us a clue as to the kind of shelter smaller creatures need to survive harsh weather.  Ready made insect shelters are now available in just about every mail order catalogue, whether it specialises in gardening products or not.  While these can be fun for children learning about the natural world, by and large they are an unnecessary expense for the wildlife gardener.  It is easy to make your own bee and ladybird shelters and others – butterfly homes for example – simply don’t work and are a waste of money.  Perhaps more importantly, we should be conscious of the natural places around our gardens and allotments which these creatures may use for hibernation, make sure there are plenty of these nooks and crannies and most important of all, ensure that they are left completely undisturbed. 

Razing borders to the ground in the autumn to ‘tidy them up’ has happily become a thing of the past in most gardens.  The idea that we leave all seed heads and other vegetation standing through the winter is, I suspect, something of a fashion statement amongst celebrity gardeners but to the rest of us it makes perfect sense - there is no doubt that it creates areas of great benefit to wildlife.  Cutting back herbaceous borders in autumn may make for a neat garden through the winter, but in doing so you are destroying lots of sheltered sites for all sorts of invertebrates as well as the occasional hedgehog.  Seed pods of many cottage garden plants and wildflowers will house ladybirds and other small beetles, as well as providing plenty of interest in the frosty winter garden.  Hollow stalks are also a brilliant refuge for hibernating invertebrates, and plenty of plants have these natural cavities within their stems.  Leaving them all standing will shelter many creatures which in turn may feed others.  If small spiders or over wintering aphids have made their winter home here, blue tits, great tits, wrens and robins will seek them out at a time when natural food is scarce.  Leaving winter stems generally means that the soil is also left alone, not turned over in the traditional way. 

Pull out the odd weed by all means but beneath the soil surface many soil dwellers find protection.  However if you are plagued with small slugs, leatherjackets or wireworms, you may prefer to expose these in the vegetable garden to your local robins and blackbirds although it may mean the sacrifice of more friendly and useful creatures. 

If you have long grass with wild flowers in your garden you hopefully found time to cut it in September, or October is not too late as long as the month is not very wet.  Neglecting these ‘haymaking’ tasks in autumn means that over time the quality of your meadow will decrease and a once floriferous area can become a sea of grass, which is a less useful wildlife habitat at all times of year.  But whatever type of garden you have, by leaving at least some long grass standing through the winter you will ensure that the diversity of invertebrates in your plot is maintained and even increased.  These winter grassy places (similar to ‘beetle banks’ left in arable areas by farmers) do exactly what the name implies – protect beetles and other insects.  It is possible for an area such as this to include flowers as long as it is cut without fail in the spring.  More robust meadow plants, including knapweed, meadowsweet, field scabious, meadow cranesbill and wild marjoram, will survive this neglect as long as a spring cut and rake is performed.  Cutting in late March or April means that the large numbers of creatures that have over wintered in your beetle bank, (including voles and slug-eating shrews) will be able to avoid your activity, or if left in the cuttings will have time to find alternative shelter before you return to remove the hay.

Log piles are renowned for their ability to shelter wildlife of all types, shapes and sizes.  Piles of rotting logs provide a home throughout the year for an almost endless list of creatures including wood boring beetles and their larvae, woodlice, spiders and worms, as well as animals higher up the food chain especially newts, toads and slow worms.  This is a really important habitat in the winter providing a cool, damp but sheltered environment where many invertebrates can hibernate.  Again the key to maintaining this as shelter is leaving everything alone except to perhaps add more logs gently to the pile as older ones decay and break down.   Animals will naturally take shelter in a wood pile waiting for the wood burner or fireplace, but this drier habitat is more likely to attract larger insects, for example butterflies and mason bees.  These insects hibernate in a variety of ways depending upon the species.  Brimstone, small tortoiseshell, comma and peacock butterflies survive the winter as adult insects, tucked away in wood stores, dried leaves, cracks in fencing and bark or in the dark corner of a garden shed or garage.  Surviving a long cold winter in this way explains why we see such sad tattered specimens in the spring.  Other butterfly species may spend the cold months as a tiny caterpillar (common blue) or a pupa (orange tip) so these creatures are especially vulnerable in the next few months.  Access to frost free places including the garden shed is essential for them.  Mason bees over winter as tiny pupae sealed within holes on logs, canes, hollow stems or ready made bee homes and bumblebee queens sleep the winter away in hollow chambers underground.  Of course as well as having plenty of natural shelter around for butterflies, bees, ladybirds, lacewings and hoverflies, you can make your own natural shelters in true Blue Peter style (no sticky-back plastic required!).  Short sections of bamboo canes, hollow plant stems and twigs can be tied into bundles and pushed into hedge bottoms, forks of trees, logpiles and dry corners of a shed to accommodate ladybirds and lacewings.  You could make sure that bird nest boxes have dry bundles of grass or wood shavings in them – these will not only habour insects but may be used by roosting wrens or tits. 

Mostly though, leave your garden alone as much as possible – slightly dishevelled, a little overgrown and undisturbed - to allow these useful creatures, upon which most of your more conspicuous garden wildlife depends for food, to spend the winter as nature intended, deep in the leaf litter, tufts of grass and thick herbaceous vegetation until spring awakens that brimstone or queen bumblebee to bring you joy next year.

© Text and photographs Jenny Steel 2012