Sturmia bella

8-11mm. Overall dark-coloured but with large grey dusted patches on the abdomen. The thorax is grey with four dark lines. All legs are dark and the hind tibiae have an anterodorsal fringe of hairs. The palps and antennae are dark.

• 8-11mm
• bare eyes
• dark with shifting grey dusting abdomenal tergites 3 and 4
• hind tibiae with anterodorsal hair fringe - as long or longer than the tibial width
• palps and antennae dark with the 3rd antennal segment 3x longer than wide
• thorax grey with 4 stripes (vittae) + 4 pairs of post-sutural dorsocentral bristles
• scutellum brown (males) and grey with a brown tip in females - with 3 pairs of marginal bristles and 1 pair of crossed apical bristles

Often seen near Nettles where caterpillar larvae are feeding.

Early May to mid October (peaking mid July to mid September)

This is a parasitoid of Nymphalid butterflies (Small Tortoiseshell and Peacock especially). Females lay eggs on nettles near to feeding butterfly larvae which then ingest the eggs. The fly larvae then feed on the internal organs before 'abseiling' to the ground to pupate.

New to the UK in 1998 but has been expanding rapidly.

Uncommon or under-recorded.

The Sturmia bella controversy, Chris Raper - is this species responsible for the decline of Small Tortoiseshells?