Field Guide
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Silver-studded Blue
Plebejus argus
Not yet photographed by the community
Silver spots on hindwing underside; heathland specialist.
Species Profile
Amber List (specialist species declining due to habitat loss and fragmentation)
- Lifespan
- 2–4 weeks as adults; larvae overwinter and can remain dormant for extended periods
- Size & Weight
- Wingspan 24–28 mm
- Habitat
- Open heathland, grassland, and moorland with low-growing vegetation, particularly areas with bird's-foot trefoil and gorse.
- UK Distribution
- Resident and locally distributed across southern England, Wales, and scattered populations in the Midlands and Southwest. Absent from northern England and Scotland. Resident with single or double broods depending on location and weather.
- Diet
- Larvae feed primarily on bird's-foot trefoil and other Lotus species; adults feed on nectar from low-growing flowers.
- Predators
- Birds, spiders, parasitic wasps, and small reptiles
- Mating Season
- May to August (June to July peak)
- Breeding
- Females lay single eggs on host plants; larvae develop through summer and overwinter as pupae or late-instar larvae. Two generations per year in southern populations, one in northern range.
- Behaviour
- Males are highly territorial, perching on vegetation and chasing rivals; they engage in a distinctive 'patrolling' behaviour to locate females. Males possess characteristic silvery spots on the underwing that give the species its name. The species is closely associated with specific foodplants and ant species that tend larvae.
- •The larvae have a symbiotic relationship with certain ant species (particularly Lasius and Myrmica spp.) which 'farm' the caterpillars for their sweet secretions
- •Males display iridescent blue upperwings while females are predominantly brown with blue scaling at the wing base
- •The silver spots visible on the underside of hindwings are reflective scales that may help with thermoregulation or predator avoidance
- •Populations are highly localised and sedentary, with individual butterflies rarely dispersing far from their natal site
- •This species requires warm, sunny conditions and is particularly vulnerable to cold, wet summers which can devastate larval development
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