Caterpillars are the eating and growing stage of the butterfly or moth.
While a few might be considered minor pests because they nibble prize leaves or veg, most are discreet and secretive, feeding only on their allotted wild plants in quiet corners. Some however, including box tree caterpillar, can devastate plants.
Not all caterpillars are hairy (a defence against being eaten by birds, some of which choke on the bristles), with many being camouflaged like leaf curls or twigs, or warningly coloured (aposematism) to show that their bodies have stored distasteful chemicals from poisonous leaves.
When fully grown, most descend to the ground and burrow into loose soil to spin a silk cocoon for the chrysalis, in which the earth-bound maggot magically transforms into an aerial adult.
More garden wildlife identifiers:
Identify the caterpillars spotted in your garden with our illustrated guide.
Poplar hawk-moth (Laothoe populi)
65-70mm. The sleek, plump, heavy body is green, sometimes with a glaucous blue or turquoise sheen, with slim, pale, diagonal flashes and pinkish spots along each side of the back. Pale-pink tail horn. Feeds on white poplar and willows.
Elephant hawk-moth (Deilephila elpenor)
85-95mm. A bronze, brown to greenish body, with eye spots behind head and tail thorn. If disturbed it squeezes front segments into a narrow trunk, inflating eye-spots into a snake-like head. Eats several plants including willowherbs.
Garden tiger moth (Arctia caja)
60-70mm. Upper body is black, ruddy brown below, with long, pale hairs all over. The archetypal hairy caterpillar, this ‘woolly bear’ has a mesmerising undulating gait. Eats a variety of food plants, including nettles, docks and hound’s tongue.
Cinnabar moth (Tyria jacobaeae)
25-30mm. Has yellow and black bars with sparse, long, pale hairs. Shreds its food plants to bare stalks, leading to local population crashes. Feeds on ragworts, including groundsel and coltsfoot. Sequesters ragwort poisons, so also poisonous.
Vapourer moth (Orgyia antiqua)
35-40mm. A psychedelic, animated boot brush, with prominent short, yellow or orange dorsal tufts, and a long, black head and tail whisker fluffs. Eats deciduous trees and shrubs, including cotoneaster and pyracantha.
Mullein moth (Cucullia verbasci)
45-50mm. The plump, pale creamy-green body has yellow blotches and stark black spots. Eats mulleins, figworts and occasionally buddleia. Heavy infestations will shed leaves to bare stalks. Poisonous, so feeds openly during the day.
Brown China-mark moth (Elophila nymphaeata)
12-15mm. Has a smooth, pale-cream or beige body. Hatchling larva mines inside leaf, then cuts and glues two oval leaf fragments with silk to make a floating case. Eats pond plants such as frogbit, water plantain, or bur reed.
Drinker moth (Euthrix potatoria)
65-75mm. Looks like a gold and blue blanket, with short tufts of black along back and a frayed white skirt. Likes common grasses such as cock’s foot. Named for supposed habit of supping dew drops.
Holly blue butterfly (Celastrina argiolus)
15-18mm. Its squat, plump, silky-green body has tinges of pink. Spring larvae feed on holly buds; summer/autumn caterpillars on ivy flowers, but in urban gardens will alternate on pyracantha and snowberry.
Browntail (Euproctis chrysorrhoea)
30mm. Black, streaked with whitish marks down each side and two orange bumps near tail; each segment with hair tufts. Lives in a communal silk webbing ‘nest’ on brambles and hawthorn. Occasional fruit tree pest.
Comma (Polygonia c-album)
40mm. Black with back marked in orange (front) and white (back), especially pronounced nearing maturity, but blurred, and resembling a bird dropping when young. On hops, stinging nettles, elms and currants.
Did you know?
The name ‘caterpillar’ comes from the old French chatepelose, which means ‘hairy cat’.