Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Diptera
Family: Dolichopodidae
Genus: Dolichopus
Species: D. trivialis

The Common Long-legged Fly (Dolichopus trivialis) is one of the most frequently seen members of the Dolichopodidae family in the UK. Like its relatives, it is a small, slender, metallic-green fly with long legs and a fast, darting flight.

Adults are usually 3–5 mm long and have a bright green or bronze sheen with clear wings and large red eyes. Males often have slightly modified legs or wing markings used in courtship displays, while females are plainer.

These flies are most often found in damp, sunny places, such as the edges of ponds, streams, ditches, and marshes, from spring to early autumn. They are active hunters, preying on tiny insects and other small invertebrates, which they catch on vegetation or near the ground.

The larvae live in moist soil or decaying plant matter, where they feed on small organisms.

Dolichopus trivialis is a common and widespread species across Britain and much of Europe. It plays an important role as a predator of smaller insects, helping to maintain balance in wetland and grassland ecosystems.