Heath fritillary Mellicta athalia

A butterfly of open woodlands, and one of Britain's rarest

Habitat: warm sunny spots sheltered by trees or shrubs with plenty of the main foodplant, Cow-wheat

Colonies survive in just a few sites in southern England, including several in Essex to which it was reintroduced

Upperside has a network of dark lines and bars on an orange-brown background; underside paler with white bands

Males patrol woodland rides and clearings continuously with a weak gliding flight, pausing to feed

Colonies move from one clearing to another as trees shade them out; wingspan around 4 cm

Eggs laid in summer, usually under bramble leaves, in large clusters near the foodplant, mainly Common Cow-wheat

Caterpillars, black with bristly rows of cones, hibernate in groups among dead leaves, basking openly the following spring

They pupate in late Spring, adults emerging through June and July