Field Guide
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Holly Blue
Celastrina argiolus
3 photos
·1 photographer
·Common · 1 ptsBright blue; favours holly and ivy around gardens.
3 community photos of Holly Blue on Things With Wings. Top-rated shots often use around 1/250ss shutter, 300mm.
Species Profile
Green List; common and widespread in the UK with stable populations
- Lifespan
- 2–6 weeks as an adult butterfly; multiple generations per year mean individuals live only a few weeks each
- Size & Weight
- wingspan 26–32 mm; 0.3–0.5 g
- Habitat
- Gardens, hedgerows, parks, and woodlands where holly and ivy plants are abundant, from lowlands to upland areas.
- UK Distribution
- Found throughout England, Wales, and southern Scotland; resident with two to three broods per year, numbers supplemented by continental migrants in autumn.
- Diet
- Adults feed on nectar from a variety of flowers including marjoram, bramble, and bugle; caterpillars feed exclusively on holly and ivy leaves.
- Predators
- Robins, wrens, spiders, and parasitoid wasps (particularly Listroderus nyrifrons, which parasitises caterpillars).
- Mating Season
- March to October, with peak activity in spring and autumn
- Breeding
- Two to three broods per year; females lay single eggs on host plants; caterpillars take 10–14 days to develop; chrysalis stage lasts 7–10 days in summer, but overwinters as chrysalis on ivy.
- Behaviour
- Holly Blues are highly territorial and males patrol vigorously in warm, sunny weather. They have a characteristically erratic, fluttering flight. Adults are attracted to damp ground and often visit puddles to drink.
- •The Holly Blue is one of the first butterflies to emerge in spring, often seen in late February or March.
- •Spring generations feed on holly leaves; autumn generations switch to ivy, a phenomenon called 'host-plant alternation'.
- •The species has become increasingly common in gardens over the past 30 years, possibly due to increased planting of ivy on buildings.
- •Males have a distinctive bright silvery-blue upperside, while females are duller blue with darker wing borders.
- •Population numbers fluctuate dramatically year to year due to parasitism by wasps, which can devastate caterpillar populations.
Community Sightings by Month
Jan
Feb
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Camera Settings (top photos)
Shutter
1/250ss
ISO Range
400–1600
Aperture
f/f/5.6
Focal Length
300mm
