Nettles

The stinging type are a favourite foodplant of caterpillars of the Comma, Peacock, Red Admiral and Small Tortoiseshell butterflies

It is widely known that the Stinging Nettle (Urtica dioica) is the main foodplant of caterpillars of several of our largest and most colourful butterflies including the Comma, Peacock, Red Admiral and Small Tortoiseshell. The closely related, but more local, annual Small Nettle (Urtica urens) is also eaten.

Being unaffected by their sting, nettles are a good choice for caterpillars, as they offer protection from predators and from falling victim to collateral damage from herbivores, both of which are usually keen to avoid the sting.

Unfortunately not everyone shares the butterfly's enthusiasm for it, taking offence at this habit of inflicting a sting on themselves. Like Sheep's Sorrel, it is rarely included in wildflower seed mixes as it's not a member of the pollinator club - being largely wind pollinated, it doesn't produce such pretty flowers to attract pollinating insects as the related dead nettles. Having said that the pollen on the anthers of the male flower do give it a distinctive bright yellow appearance while the styles on the female flowers have a silvery, furry look.

If you recognise it as a good thing for butterflies, that's great, but do try to avoid relegating it to a shady out of the way spot at the bottom of the garden. That's not the best place for it, as butterflies seek to lay their eggs on fresh new leaves in sunny areas. One solution is to plant it in large pots. which can be moved around into sunny parts of the garden and kept out of harms way. Try trimming the plants in June, once the adult butterflies have emerged, to stimulate a fresh new growth of leaves for the second brood.

Caterpillars of several species of moth also eat nettles
It's not only butterfly caterpillars that feast on nettles. They are much sort after by several species of moth, including the Mother of Pearl, Burnished Brass, Jersey Tiger, Golden Y and Snout Moth, as well as numerous other invertebrates - over a hundred have been identified on nettles - and of course these in their turn provide food for garden birds and their chicks.
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Once we get to know them, maybe with the aid of a magnifying glass or an enlarged digital photo all these invertebrates are as fascinating in their own right as butterflies.

If you don't have any nettles in your garden already you can collect some seeds, or grow them from cuttings. Just cut off some newish stems about seven or eight inches long, remove the bottom leaves and place in a jar of water to root. Once rooted they can be planted in pots for moving later to their final destination.

INCREASE BIODIVERSITY BY GROWING NETTLES TO SUPPORT THE BUTTERFLIES BELOW

SMALL TORTOISESHELL
Aglais urticae

Fastidious in its food requirements, the caterpillar of the Small Tortoiseshell feeds almost exclusively on the leaves of stinging nettles. It folds the leaves over itself as a protective tent while it feeds.

COMMA
Polygonia c-album

For caterpillars of the Comma Butterfly (Polygonia c-album), while Stinging Nettle is the main foodplant, there is a different and perhaps surprising alternative. Hops (Humulus lupulus).

The liking of Comma caterpillars for hop leaves was common knowledge in the past when hops were grown throughout Britain for local brewing purposes, and several local names for the butterfly reflect this.

When feeding on the leaves of stinging nettles, the caterpillar, like that of the Small Tortoiseshell, folds them over itself as a protective tent.

PEACOCK
Inachis io

The Peacock butterfly lays its eggs in batches on the leaves of Stinging Nettles. The caterpillars have also been observed feeding on hop leaves and will do so in captivity.

RED ADMIRAL
Vanessa atalantica

The stinging nettle is the main foodplant of the caterpillars of the Red Admiral.

They too have been observed feeding on hop leaves.

The much rarer PELLITORY OF THE WALL, a non-stinging relative of the stinging nettle, is another option for this butterfly.

Potential Alternatives to Nettles

Grow Your Own Hops
As caterpillars of the COMMA butterfly are well known for feeding on hop leaves, and those of the PEACOCK and RED ADMIRAL have been seen doing so, why not grow a hop plant or two along with the nettles to see whether any of these butterflies choose them to lay their eggs on. 

The hop is a fascinating plant, especially the female form with its long tassels of seed pods, grows rapidly, and like the nettle is a food plant for dozens of other invertebrates, so it's well worth a try. Seeds and plants are readily available from garden centres and on-line suppliers, and they don't sting.

For caterpillars of the RED ADMIRAL, an alternative is Pellitory of the Wall (Parietaria judaica). This perennial plant has a liking for cracks in old stone walls such as those of churches and abbeys or even those in your own garden. It is also found on cliff faces where little else can gain a foothold. When we realise that despite its different habitat, it's a member of the nettle family closely related to the stinging nettle, its attraction to the Red Admiral caterpillars is clear. Its stem and leaves are very hairy but they don't sting,

Grow your own Pellitory on the Wall
The seed is not easy to obtain commercially, so you may need to get hold of it from the plant itself. Seedlings will grow in most kinds of soil, but final planting among rubble or into gaps between the stone of walls will give them a competitive advantage.

Non-stinging Stinging Nettles
Surprisingly there is a variety of non-stinging stinging nettle in which the stinging hairs are almost completely absent. Rare overall it is common in certain locations, including Wicken Fen in Cambridgeshire.