Found in tall dry grassland
Sedentary. Expansion due to:
- A recent coloniser? Discovered 1890
- Climate change
- Eggs hitching lift on long distance road haulage of hay
- Steep grass-covered embankments on motorways and major roads acting as corridors
Needs compact tightly-furled leaf – not Yorkshire-fog (a species of grass)
Pupation in silk cocoon enclosed within tent of leaves at base of foodplant
Eggs hatch in year following laying.

In olden days known as the “Golden hog”
The male has a sex brand on its forewings containing specialised scent scales
Larvae hatch before entering hibernation (unlike Essex Skipper)
Predominantly uses Yorkshire-fog as foodplant
Found where grasses allowed to grow tall
Study showed 2/3 of population move less than 20m per day
Less affected by drought than many species but is vulnerable to regular cutting of grasses

Not just grassland – found in woodland rides, landfill, urban areas (scrubby areas)
Prefers foodplant (Cock’s-foot – a grass) in damp area and in tall / uncut form
Pupae formed among leaf blades
Vulnerable to grass cutting
Males, seeking a mate:
- Early morning and afternoon: use traditional perch (used by several males)
- Mid- to late morning: go on patrol

‘Traditionally’ laid eggs after hay crop cut
Flies in dull weather
Larvae overwinter – may feed in mild weather
- Young initially feed in the day
- Spring larvae feed nocturnally
Colonies lost through agricultural intensification. Also lack of management in woods.
A thriving colony has over 2 000 adults per hectare. (In Long Meadow 50+ adults / hectare is the norm.)

Foodplant – Common bird’s-foot trefoil
Larvae in final instar are attractive to ants – but the Common blue is not seemingly dependent on ants
Suffers from intensification of farming – replacement of herb-rich grassland by rye grass or arable crops
A small colony may survive in an area of 0.5 to 1.0 hectare
Vegetation must not be too tall – a mix of tall (max 15cm) and low swards needed – best achieved by grazing.

Where present prefers Common rockrose. Elsewhere (Abbey Fields) Dove’s-foot Crane’s-bill, perhaps also Cut-leaved Crane’s-bill.
Eggs laid where turf is 1 to 10cm tall, on underside of leaf
Always attended by ants, feeding on sweet secretions. (It is thought mainly red ants and black ants are involved.)
Hibernating larvae and pupa covered in earth cells by ants.

Decline linked to climate change (the butterfly is still thriving in the north of Britain)
- Warmer weather is causing generations to hatch out too late in the year to survive.
- First generation historically less numerous than second (July to September) generation
- Populations have retreated to the coast
A butterfly that appears to like the sun (when not too hot) and selects dry and stony areas for basking and egg laying
Many inland habitats unsuitable following abandoning traditional grazing
- Grazing animals needed to break up sward for good breeding conditions
- Eggs laid amongst broken turf.

Grassland Butterflies