West Sussex, 7 May 2016
Green Hairstreak (Callophrys rubi)
C.rubi is the most widespread of the British hairstreaks. However, it is also a local species, forming distinct colonies, which can be as small as a few dozen individuals, although larger colonies exist. During good seasons the adults can be locally very common on the West Sussex downs.
Both sexes always settle with their wings closed, the brown uppersides only ever being seen in flight when they can be notoriously difficult to follow. The undersides, by contrast, provide the illusion of being green, an effect produced by the diffraction of light on a lattice-like structure found within the wing scales, which provides excellent camouflage as the butterfly rests on a favourite perch. The sexes look very similar and are most readily told apart in the field by their behavior. Rival males may often be seen in flight close to shrubs, while the less conspicuous females are more often encountered whilst egg laying.
A male defending his territory is depicted above …