25/08/2026
It's been a bumper summer for butterflies, keep an eye out for their caterpillars and encourage patches of nettles which feed a lot of them.
The caterpillars that turn up on garden plants, walls, sheds and pots are, for the most part, larvae of butterflies and moths that are part of the food chain — feeding song thrushes, blue t**s, wrens, hedgehogs, ground beetles — and quietly turning into some of the most beautiful things in a British garden.
Identifying the ones you are most likely to find:
🐛 Peacock (Aglais io) — velvety jet-black caterpillar densely covered in tiny white speckles and lined with fine branching black spines. Feeds gregariously on nettles under a communal silk web.
🐛 Small tortoiseshell (Aglais urticae) — similar in build to the peacock, black with pale yellow streaks along the sides and shorter dark spines. Also lives in groups on nettles.
🐛 Red admiral (Vanessa atalanta) — spiny caterpillar, colour variable from black to olive-green to reddish-brown, always with a pale cream stripe along each side. Feeds singly, folding itself into a tent made from a single nettle leaf.
🐛 Painted lady (Vanessa cardui) — dark greyish-brown caterpillar with a pale yellow lateral stripe and short spines, feeding on thistles inside a loose silk web. This one is a migrant — the adults arrive in Britain from North Africa each summer.
🐛 Comma (Polygonia c-album) — spiny caterpillar with a striking large white saddle across the middle of its back, giving it a distinctive resemblance to a bird dropping. Feeds on nettles, hops or currants.
🐛 Brimstone (Gonepteryx rhamni) — plain smooth mid-green caterpillar with a paler stripe along each side, camouflaged perfectly along the midrib of a buckthorn or alder buckthorn leaf where it feeds. The adult butterfly is the pale primrose-yellow one that flies as early as March.
🐛 Elephant hawk-moth (Deilephila elpenor) — the most spectacular caterpillar in a British garden. Fat, up to 8 cm long, thick-bodied, dark brown or green, with two large false eyespots near the head that make it look startlingly like a snake when disturbed. Feeds on rosebay willowherb, fuchsia and bedstraws.
⚠️ Two caterpillars in Britain do need caution — but not for their appetite. It is their hairs.
The oak processionary moth (Thaumetopoea processionea) has been spreading across southern England from London since the early 2000s and is now the subject of a Forestry Commission control programme. The caterpillars live communally in silk nests on the trunks and branches of oak trees, and move up and down the trunk in the head-to-tail processions that give the species its name. Their fine hairs contain thaumetopoein, which causes skin rashes, eye irritation and breathing problems in some people. Never touch the caterpillars, their nests, or a tree that has them. Report sightings to the Forestry Commission's Tree Alert system.
The browntail moth (Euproctis chrysorrhoea) is a smaller but genuinely irritating British native, mostly found on hawthorn, bramble, blackthorn and roses in southern England. Dark hairy caterpillars with a pair of small red spots near the tail. The hairs also cause skin rashes. Same rule: look, don't touch.
Both are the exception. Almost every caterpillar you find on a British garden plant is safe to hold, safe to relocate onto its correct food plant if you find it wandering, and worth leaving alone if you can. What eats a few leaves in summer is what feeds the song thrushes and lays the eggs of next year's peacocks 🦋
