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Phasia hemiptera on an umbellifer flower. It's a colourful orange and purplish-black fly with broad, irridescent wings

Phasia hemiptera © Tom Hibbert

Bat-winged phasia

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This colourful fly can be found on flowers in wooded areas.

Enw gwyddonol

Phasia hemiptera

Pryd i'w gweld

April to October

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Stats

Wing length: 7-11.5 mm

Ynghylch

The bat-winged phasia is a colourful fly found around wooded areas across the UK, where it often visits umbellifers and other flowers. Males look quite different to females, with oddly curved wings that are shaped a little like those of a bat.

The bat-winged phasia is a parasitoid of shieldbugs. It is known to target both green shieldbugs and red-legged shieldbugs. The female lays an egg on a bug, the egg hatches and the larva burrows inside of it. The larva then develops within the shieldbug, feeding on and eventually killing its host.

What to look for

A fairly large and colourful fly, with large red eyes and a brush of golden hairs each side of the thorax. Males have a slightly flattened appearance to their body, which is dark bluish-black with reddish-orange sides. Their wings are broad and oddly curved, with irridescent patches. They are highly variable in size and colour and some can have entirely dark wings. Females are smaller, appear less flattened and have narrower wings without the dark, irridescent patches.

Where to find

Widespread in the UK. Also found on Isle of Man and the Channel Islands.

Roeddech chi yn gwybod?

The bat-winged phasia has been recorded spreading northwards through Europe, possibly benefitting from a warming climate. In 2006, it was found in Norway for the first time.