Green Hairstreak, Callophrys rubi

Identification

Wingspan 30mm to 35mm.

Both sexes exhibit similar colour-patterning. The upper surfaces of the wings, which are never seen when the butterfly settles, but glimpsed when it is in flight, are a plain dull brown. The under-side is a very bright copper green. There is a row of white spots running across the hind wing and the edges of all wings are margined white interrupted with dark brown bars. These dark bars increase in intensity along the margin of the hind wings and end in a small black-tufted tail with a white base.

Behaviour and life history

The males are very territorial and adopt perches, often overlooking small clearings, from which they swoop down in an erratic fashion to defend their territories, before returning to their perches. Due to their colouring they can be very difficult to find on their perches. Green Hairstreaks over-winter as chrysalises underground in ants nests. Adults emerge in late April and early May, laying their eggs in May and June. Caterpillar development is completed by the end of July. It pupates on the ground and the chrysalis is harvested by ants which drag it into their nests to feed off its secretions. In this part of the country, the main food plants are gorse (Ulex spp), Bilberry (Vaccinium myrtillus) and Birds-foot Trefoil (Lotus corniculatus).

Where to look for it

It prefers relatively dry, rough ground with plenty of scrub, especially gorse. It has been recorded from the Billacombe and Turnchapel areas of Plymouth in the past and, more recently, just a few hundred metres outside the city boundary at Jennycliff.

Distribution and status

Very rare, it possibly no longer breeds in the City and any specimens seen are likely to be casual visitors.

When to look for it

Adults are on the wing between late April and early July with numbers peaking at the end of May.

Similar species

The green undersides of the wings make this species unmistakeable.

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