The Sciomyzidae is another one of the less common families of true flies in our fresh waters. Their larvae are maggot-like, but the body is characterised by a very “bumpy” outline. There is no visible head, but there is a spiracular disc (breathing structure) at the end of the abdomen.
Sciomyzid larvae are most likely to be found in slow flowing weedy streams, wetlands, ponds or lakes.
The sciomyzids are predators, preying primarily on molluscs, including sphaeriid bivalves and snails.
The ability of sciomyzids to tolerate slow-flowing, low-oxygen habitats allows them to live in waters of relatively poor quality. They therefore have low tolerance values of 3 for both hard and soft bottom sites.