The Purple-brown Hairstreak is one of the Lycaenidae (Gossamer-winged Butterflies), subfamily Polyommatinae (Blues, Bronzes, Hairstreaks etc.). Hairstreaks are among the larger members. 

The male Purple-brown Hairstreak’s wingspan is 22-28 mm, the female’s, 24-31mm.

Males choose a perch on the side of a bush or on a prominent rock and fly off to chase other butterflies. They fly extremely fast but settle often and readily open their wings to reveal the upper side. This appears to be plain brown until the sun catches it, then it shows purple iridescence. The females look different; they are plain brown with a patch of grey-blue on the forewings and bands of white along the hindwing upper side outer edge. Females fly at a slower pace and are more frequently observed on flowers compared to males. Both sexes have two long filamentous tails at the end of their hindwings. These are located adjacent to a fold on the wing, positioned at right angles, and feature a black spot resembling an eye. Especially when seen from behind by a predator, like a bird, which might peck at the wrong end of the butterfly. When the butterfly is at rest it rubs its hindwings together which makes the tails move as if they were antennae.

To make the deception even more effective the underside has thin stripes (‘Hairstreaks’) that lead the eye to this ‘false head.’