In Britain and Ireland the distinctive Green Hairstreak is unlikely to be mistaken for any other native butterfly. The white streaks on the green undersides of the forewing and hindwing are usually intermittent and sometimes almost imperceptible. (The green appearance is in fact illusory and caused by diffraction of light impinging on a lattice-like structure within the surface scales.) At rest the wings are always held closed so that the upperwings, which are a dull orange-brown, are visible only when the butterflies are in flight. Males and females look very similar, differing perceptively only in body shape; they have a typical wingspan of 3cm.
The Green Hairstreak is found throughout Britain, Ireland and most of mainland Europe as well as many parts of Asia and northern Africa. Scrubby grassland, hedgerows and chalk downland are typical of the habitats favoured by this distinctive butterfly, but small colonies are also found on acidic heathland. Green Hairstreaks are fairly common in coastal and inland regions of southern Portugal, where the specimens shown on this page were photographed.
Green Hairstreak butterflies emerge from their chrysalises in late March and can be seen on the wing through to the end of June and sometimes well into July. This species has just a single brood. Its larval foodplants are very varied but, depending on habitat, can include Rock Rose, Lesser Bird's-foot Trefoil, Heather and Gorse. From green eggs that are laid singly, the larvae, which are green with black markings along their backs, develop rapidly before spending the winter months in the pupal state.
This page includes pictures kindly contributed by Rob Petley-Jones.
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