Field Guide
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Purple Emperor
Apatura iris
Not yet photographed by the community
Magnificent canopy butterfly; males flash iridescent purple.
Species Profile
Red List (Nationally Scarce A); priority species for conservation in the UK due to severe habitat loss and population decline.
- Lifespan
- Approximately 2–3 weeks as an adult butterfly
- Size & Weight
- Wingspan 48–55 mm
- Habitat
- Woodland edges, clearings, and sallow carr (willow scrub) where the larval food plant grows abundantly.
- UK Distribution
- Highly localised resident found in southern England, primarily in the Midlands, Hampshire, Sussex, and Kent. Populations are fragmented and restricted to specific woodland sites.
- Diet
- Adults feed on fermenting fruit, tree sap, and dung; they rarely visit flowers. Caterpillars feed exclusively on goat willow (Salix caprea) and occasionally pussy willow (Salix discolor).
- Predators
- Birds including flycatchers and thrushes; small mammals may predate pupae.
- Mating Season
- June to August
- Breeding
- Single brood per year; females lay eggs singly on willow leaves; caterpillars pupate in late summer; pupae overwinter and emerge in early summer.
- Behaviour
- Males are highly territorial, patrolling woodland clearings and perching on tree trunks or low branches. They engage in spectacular aerial chases and rarely come to ground. Females are more reclusive, staying in the canopy to lay eggs on willows.
- •The male's iridescent purple sheen on the wings is caused by light-refraction from specialised wing scales, not pigmentation, and appears to glow in sunlight.
- •Purple Emperors have a peculiar behaviour of feeding on bird droppings and animal dung, which provides essential salts not found in nectar.
- •The species is named after its regal appearance and purple coloration, which is only visible in males when viewed at certain angles.
- •UK populations have declined by over 90% in the past 50 years due to loss of mature woodland with sallow understorey.
- •Adult Purple Emperors are remarkably long-lived for a butterfly, sometimes surviving 3–4 weeks, and can fly in relatively cool conditions compared to other British butterflies.
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