Callophrys rubi can be first seen at the end of March, with flight duration usually lasting until the end of June, although they are sometimes seen in July and early August.
   They never rest with their wings open, to maintain their green camouflage.
   The males are quite territorial.
   Their wide range of food plants means that Green Hairstreaks are able to use a wide range of habitats including chalk downland, heathland, moorland and clearings in woods. They are present in wetlands as well as on dry meadows, at an elevation of about 0–2,300 meters (0–7,546 ft).
   The dorsal sides of the wings are a uniform dull brown, with two pale patches on the male's forewings made up of scent scales.The ventral sides are a bright green with a thin white line, often reduced to a faint row of dots or even missing altogether. The iridescent green color of the undersides is a structural color caused by diffraction and interference of light refracted off the wing scales.
   The caterpillars are green with yellow markings along the back. Like other members of the family they are somewhat slug like.