Caterpillars

Here is a curated list of the larger caterpillars found in Highland Perthshire — butterflies and moths only — with descriptions, food plants, and when you're most likely to see them.

Butterflies

1. Peacock — Aglais io

• Size: Up to 42 mm

• Description: Velvety black with fine white speckles and rows of branching black spines along the back and sides; gregarious when young

• Food plant: Stinging nettle (Urtica dioica), occasionally hop

• When: June–August; most obvious late July into August

2. Small Tortoiseshell — Aglais urticae

• Size: Up to 35 mm

• Description: Black with yellow/grey markings and black spines; similar to Peacock but with clearer yellow speckling; also feeds in groups

• Food plant: Stinging nettle

• When: June–September; two broods in good years

3. Comma — Polygonia c-album

• Size: Up to 34 mm

• Description: Dark black with fine spines and a bold white saddle-patch on the back — strikingly resembles a bird dropping; solitary

• Food plant: Stinging nettle, also elm, willow, birch, currants

• When: June–July; expanding range in Perthshire

4. Marsh Fritillary — Euphydryas aurinia

• Size: Up to 30 mm

• Description: Black with fine hairs and orange-red markings; lives communally in a tough silken web over winter; conspicuous in spring before dispersing

• Food plant: Devil's-bit Scabious (Succisa pratensis)

• When: August–June (overwinters small within web; feeds vigorously April–May)

5. Red Admiral — Vanessa atalanta

• Size: Up to 35 mm

• Description: Black with pale yellow speckling along the back and branching spines; older caterpillars may have a yellow stripe along the sides; solitary, fold leaves together for shelter

• Food plant: Stinging nettle (Urtica dioica), occasionally hop

• When: July–October; migrant from southern Europe/North Africa — numbers vary greatly year to year; does not survive winter as caterpillar in Scotland

6. Orange-tip — Anthocharis cardamines

• Size: Up to 32 mm

• Description: Pale green with a faint white line along each side; slender and well camouflaged; strongly resembles the seed pods of its food plant — excellent disguise

• Food plant: Garlic mustard, cuckooflower, hedge mustard, bittercress — prefers damp meadow/stream-side plants

• When: May–June; caterpillar grows rapidly then pupates for 10 months; single brood only

7. Pearl-bordered Fritillary — Boloria euphrosyne

• Size: Up to 28 mm

• Description: Black with dense short bristles and orange-brown markings along the back; overwinters while still small and barely feeding; becomes conspicuous April–May

• Food plant: Common Dog-violet (Viola riviniana) — requires warm, sunny, open ground around plants

• When: July–May; hibernates tiny among dead vegetation; feeds vigorously spring before pupating; very localised — needs bracken or scrub clearing to keep habitat open

8.  Small Pearl-bordered Fritillary — Boloria selene

• Size: Up to 28 mm

• Description: Black with fine hairs and reddish-brown markings; very similar to Pearl-bordered but generally darker; overwinters small

• Food plant: Marsh violet (Viola palustris) and Common Dog-violet — favours damp, boggy or wet grassland

• When: August–May; single brood; more widely distributed than Pearl-bordered where suitable wet habitat exists

9. Scotch Argus — Erebia aethiops

• Size: Up to 28 mm

• Description: Pale brownish-green with darker green and whitish lengthwise stripes; head pale brown; slow-growing and well camouflaged among grass blades

• Food plant: Purple moor-grass (Molinia caerulea) — the main plant; also tufted hair-grass and other coarse grasses

• When: September–June; overwinters half-grown; feeds spring then pupates low in vegetation; characteristic of moorland and damp grassy glens

10.  Northern Brown Argus — Aricia artaxerxes

• Size: Up to 20 mm

• Description: Pale green with a darker green stripe along the back and pinkish/whitish stripes along the sides; flattened shape; tended by ants which protect it

• Food plant: Only Common Rock-rose (Helianthemum nummularium) — found on limy, south-facing slopes

• When: August–May; overwinters small; feeds March–May; restricted to limestone/calcareous grassland — present in parts of Perthshire but local

11.  Speckled Wood — Pararge aegeria

• Size: Up to 27 mm

• Description: Bright fresh green with faint darker green and yellowish stripes along the body; short forked tail at rear; feeds mostly at night

• Food plant: False brome, Yorkshire fog, cock's-foot and other woodland grasses

• When: Can be found almost year-round — uniquely overwinters as either caterpillar or chrysalis; several overlapping broods March–October; the butterfly of dappled shade

12. Green Hairstreak — Callophrys rubi

• Size: Up to 16 mm

• Description: Bright green with darker chevron markings along the back; distinctly flattened shape; very well camouflaged; solitary

• Food plant: Exceptionally wide choice — bilberry, cowberry, bird's-foot-trefoil, bramble, rock-rose, gorse, heather, broom

• When: May–June; single brood; feeds briefly then pupates at ground level; found on heath, moor, scrub and woodland edges

Moths

1.  Elephant Hawk-moth — Deilephila elpenor

• Size: Up to 85 mm — one of our largest

• Description: Thick-bodied; usually grey-brown (sometimes green) with four large prominent false "eyespots" behind the head and a short blunt horn at the rear; retracts head to look like a snake

• Food plant: Rosebay willowherb, Great Willowherb, bedstraws, garden Fuchsia

• When: July–September; frequently encountered crossing paths

2. Poplar Hawk-moth — Laothoe populi

• Size: Up to 70 mm

• Description: Bright lime-green with faint yellow diagonal stripes along the sides and a curved yellow horn at the tail; skin feels granular

• Food plant: Aspen, poplars, willows, sallows

• When: July–September; sometimes a partial second brood

3.  Emperor Moth — Saturnia pavonia

• Size: Up to 65 mm — the largest native moth caterpillar

• Description: Boldly banded bright green and black with pink/golden-yellow tufted warts along each segment; highly distinctive

• Food plant: Heathers, bilberry, bramble, blackthorn, birch, meadowsweet

• When: July–August; moorland and heathland species, common around Rannoch

4. Fox Moth — Macrothylacia rubi

• Size: Up to 70 mm

• Description: Very furry; dark grey-brown sides, rich orange-brown along the back with long tawny hairs; fully grown caterpillars overwinter and emerge basking in early spring

• Food plant: Heather, bilberry, bramble, meadowsweet, various low-growing plants

• When: Late summer–autumn, then March–April (basking) before pupating

5. Oak Eggar — Lasiocampa quercus

• Size: Up to 65 mm

• Description: Large, furry and robust; rich golden-brown with black bands between segments and a row of pale whitish dashes along each side; similar to Fox Moth but darker with clearer side markings

• Food plant: Bramble, heather, bilberry, sallows, hawthorn — not restricted to oak

• When: July–June; overwinters as small caterpillar, grows rapidly May–July

6.  Garden Tiger — Arctia caja

• Size: Up to 50 mm

• Description: Very hairy; dark brown/black with longer grey-brown hairs and a reddish-brown stripe along the back; known as a "woolly bear" — rolls into a ball when disturbed

• Food plant: Wide range including dock, plantain, nettle, ragwort, honeysuckle

• When: Autumn then again March–May before pupating

8. Cinnabar — Tyria jacobaeae

• Size: Up to 30 mm

• Description: Bright warning colours — bold rings of black and vivid orange/yellow; feeds openly in full view; toxic from the food plant

• Food plant: Common ragwort, occasionally groundsel

• When: July–September; very conspicuous on ragwort stems

9. Drinker — Euthrix potatoria

• Size: Up to 55 mm

• Description: Hairy, tawny-brown with pale creamy stripes along the body; four tufts of longer hair near the head; overwinters small

• Food plant: Tall grasses — purple moor-grass, cock's-foot, reeds

• When: Autumn then April–June; damp grassland and moorland edges

Quick Reference Table

Species Max Length Main Food Best Months 

Elephant Hawk-moth 85 mm Willowherb, bedstraw Jul–Sep 

Poplar Hawk-moth 70 mm Willow, poplar Jul–Sep 

Emperor Moth 65 mm Heather, bilberry Jul–Aug 

Fox Moth 70 mm Heather, bramble Aug–Apr 

Oak Eggar 65 mm Bramble, heather Jul 

Garden Tiger 50 mm Dock, nettle Apr–May 

Drinker 55 mm Grasses Apr–Jun 

Peacock 42 mm Nettle Jul–Aug 

Small Tortoiseshell 35 mm Nettle Jun–Sep 

Comma 34 mm Nettle Jun–Jul 

Marsh Fritillary 30 mm Devil's-bit Scabious Apr–May 

Cinnabar 30 mm Ragwort Jul–Sep 

Notes:

• Overwintering: Several species spend the winter as caterpillars — Fox Moth, Oak Eggar, Garden Tiger, Drinker, Marsh Fritillary — so look for them basking on sunny days from late February onwards

• Irritation: Hairy species (Fox, Oak Eggar, Garden Tiger) should not be handled; hairs can cause mild skin reactions

• Local abundance: Elephant Hawk-moth is widespread wherever willowherb grows; Emperor and Fox Moth are characteristic of moorland and heath; Marsh Fritillary is localised but present in suitable damp grassland