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Encouraging Butterflies to Breed n your Garden

There has been much in the media over the last few months about the effect our last two disastrously wet summers have had on UK butterfly populations.  Surveys carried out by the organisation Butterfly Conservation have revealed that even our most common species, including the garden favourite the small tortoiseshell, have declined dramatically in some cases to the point of causing concern about their long term survival.  Those most at risk are butterflies that already have small populations in isolated locations such as the high brown fritillary, species whose requirements are very specific including the black hairstreak or butterflies on the very edge of their natural range, the swallowtail being an example.  Changes in our butterfly populations occur all the time but a decrease of 45% in the number of small tortoiseshells is cause for much concern.  Other figures from the survey reveal huge decreases in numbers of migrant species such as painted lady and clouded yellow. 

As wildlife gardeners we are used to the idea of providing nectar for everyday insects.  Many common nectar feeding insects, especially honey bees and bumblebees, pollinate our fruit, vegetables and flowers and it makes sense to welcome them to our gardens for that reason alone.  These beneficial insects along with hoverflies, ground beetles, ladybirds and lacewings have been elevated in their status over the last few years and are now seen by most gardeners as useful creatures to have around, which they certainly are.  Butterflies however are a rather different story!  Die hard allotment holders and less well informed gardeners will still persecute all butterflies (and of course moths) on the grounds that they eat everything in sight, their caterpillars nibbling away at leaves of precious plants.  But as numbers continue to decline, is simply providing nectar enough to help our native butterfly species?  As gardeners who see the wildlife around us as an important part of the garden ecosystem as a whole, what can we do to help to reverse the loss of some of our most beautiful native insects? 

  wall brown

The British Trust for Ornithology and the RSPB regularly release figures which show that garden bird feeding and the provision of nest boxes has helped our native birds.  Perhaps we can apply a similar logic to helping our garden butterflies?  Growing the usual butterfly nectar plants is a good start, but encouraging breeding is the most positive action we can take.  So how do we go about this?  Is a nettle strewn garden the logical conclusion to this idea?  First of all, useful as nettles are to some species of butterfly, there is a common misconception amongst the uninitiated that ‘leaving nettles for the butterflies’ is the only thing (excuse?) that one has to do in the garden to help these insects.  As with so many aspects of providing for our local fauna, it’s not as easy as that!

Small tortoiseshell, red admiral and peacock butterflies do all lay their eggs on nettles and the caterpillars therefore eat the leaves, plus comma and painted lady will sometimes use them although they have other preferences – comma prefers hops and painted lady, thistles.  Leaving a clump of scruffy nettles in a shady place – under a tree or behind the garden shed - will be of little use to any of these species.  Other insects (including some species of ladybird) will use nettles in this sort of situation, but butterflies are creatures of warmth and light and they like their nettles in just such a situation.  Nothing but the sunniest, warmest spot in your garden will do and fresh young nettle leaves are preferred.  Living in a rural location I don’t intentionally leave any nettles for breeding butterflies in my garden as there are masses in the fields all around me.  Inevitably these plants find their way into the garden and I keep an eye on them for butterfly activity, but most of those that grow in the shady parts are composted. 

         Peacock caterpillars on nettle leaves

However, our nettles, whether you want to grow them deliberately or not, cater for only five of the twenty or so species that you could attract to your garden.  Other larval food plants for all of these are a lot more attractive and easier to handle than the stinging nettle, so set your sights of helping some of the most beautiful of our native insects – the stunning orange tip, elegant ringlet, dazzling common blue, and wonderful butter yellow brimstone.  The orange tip is one of the ‘white’ butterflies and has declined considerably (26 %) in recent years.  This was a butterfly of wet meadows, laying its eggs on the spring flowering lady’s smock, sometimes known as cuckoo flower.  This delicate plant with its pale mauve flowers was once a common sight in country meadows along with cowslips and in some locations snake’s head fritillary.  Its other larval food choice is the hedge mustard or jack-by-the-hedge.  This useful wildflower is edible, imparting a lovely hot garlic taste to salads, or it can be cooked.  This is easy to grow at the base of a hedge, or lady’s smock will thrive in a damp patch next to a pond.  A further, very attractive alternative is honesty which this little butterfly will use in the absence of the other two species.  Useful in any wildlife garden, honesty’s violet flowers, which also provide nectar for the adult butterflies, are followed by the familiar ‘moon penny’ seed pods containing seeds so large and nutritious they will keep greenfinches entertained for ages.

Brimstone, the yellow winged harbinger of spring, is another easy butterfly to encourage to breed.  This insect is more particular than some others in terms of laying its eggs and only the two species of buckthorn, purging and alder, will suffice.  These are easy little shrubs to grow: alder buckthorn prefers damp acid soils and purging is happier on drier lime rich substrates.  The female (cream coloured) brimstone can detect the scent of this plant from some distance.  Buckthorn can be tucked into a hedge or grown amongst other shrubs.  If there are brimstones in your area, they will find it. 

The blue butterflies are a group of tiny, bright winged insects that in general live in quite specialised habitats, but the common blue is relatively easy to encourage to gardens if its larval food plants are available.  First choice is bird’s foot trefoil, which is easy to grow at the front of a border, in a scree garden, on a living roof or in short grass.  Bear in mind though that if you plant it in grass you will not be able to cut it for a couple of months in the summer.  If this sounds a bit too problematic and you have a pond, try growing greater bird’s foot trefoil – a plant of boggy meadows and waterside habitats.  The common blue will use it just as readily and it’s a lovely plant to enhance a wildlife pond.

Lastly the elegant brown butterflies. Strangely the lovely ringlet butterfly actually increased in number last summer, possibly due to the timing of its breeding season.  This lovely butterfly, together with meadow brown, gatekeeper, large and small skipper and several other species all deposit their eggs on native grasses and their caterpillars feed on the grass leaves.  Only a meadow will do for them, so leave some long grass in a sunny corner and see what happens.

Some useful information...

Helping butterflies to breed, just as we have aided garden birds such as blue tit and great tit, house sparrow and robin with carefully designed nest boxes, could well make a difference to butterfly numbers in the future.  Many common birds now rely on our gardens for food and shelter.  Maybe as conscientious wildlife gardeners, we can do the same for some of our most beautiful butterflies.  If you plant both nectar plants and larval food plants you could expect twenty or more species of butterfly to visit and use your garden instead of just a handful.

Growing Nettles  Nettles need to be in a sunny and sheltered spot for butterflies to use them.  Make sure there are young fresh leaves by cutting them back in April and don’t get your hopes up!  Nettles in gardens are not often used by butterflies although other insects will use them.  Butterflies seem to prefer larger patches in the countryside, but it is worth a try if you have space for them.

Plants for breeding butterflies  Try growing lady’s smock, garlic mustard, bird’s foot trefoil, native fine-leaved grasses such as the fescues, wild sorrel (for small copper), honesty and buckthorn. 

Make a small meadow  Leaving an area of grass in your garden uncut could encourage the butterflies that use native grasses as a larval  food plant.  Even better, take up an area of turf and sow a native grass mix.  Even without any wildflowers this will still make a good habitat for wildlife and may attract meadow brown, gatekeeper and speckled wood which are the brown butterflies that most commonly visit gardens.  Larger areas could attract skippers, wall brown and ringlet.

Don’t forget nectar flowers  Buddleia, Echinacea, catmint, sedum, michaelmas daisy, scabious – there are butterfly nectar plants for every garden.  Do a bit of research to find out what’s best for your soil.

Why butterflies don’t do well in wet weather  There are several reason why butterflies don’t thrive in poor summers.  Firstly they can’t fly in pouring rain which means there are fewer chances of feeding, mating and laying eggs, and equally important is that both eggs and caterpillars are prone to fungal diseases in damp conditions, meaning that the next generation is much reduced in numbers.