Green Hairstreak (Callophrys rubi)
C. rubi is the most widespread of the British hairstreaks. However, it is also a rather local species, forming distinct colonies, which can be as small as a few dozen individuals, although other colonies can be significantly larger. Partly due to the wide variety of larval foodplants it uses, and the wide range of habitats it frequents, C. rubi is found throughout the British Isles. However, it is absent from the Isle of Man, Outer Hebrides, Orkney and Shetland. It can be found in a wide variety of habitats, including hillsides, moorland, chalk downland, heathland, railway embankments and valley bottoms. A common feature of all these habitats is the presence of scrubby plants and hedgerows.
Both sexes always settle with their wings closed, their brown uppersides only ever being observed in flight. The undersides, by contrast, and as depicted in the image of a female above, referable to ab. bipunctata, Tutt (1907), provide the illusion of being green, an effect produced by the diffraction of light on a lattice-like structure found within the wing scales. This provides excellent camouflage as the butterfly rests on a chosen perch such as a Birch branch.
Single brooded, the adult butterfly is typically seen from mid April to the end of June, depending on location. Emergence is typically later in more northern sites where this butterfly may be on the wing into early July.