Massed Kelp Flies

Massed Kelp Flies

Observation - Massed Kelp Flies . Description: Tens of thousands of these small, flattened, bristly flies were gathered in dense swarms on shaded faces of a cliff above the strandline on a Scottish beach. Huge numbers of cocoons were among the seaweed below the cliff. I doubt it's possible to ID the

Tens of thousands of these small, flattened, bristly flies were gathered in dense swarms on shaded faces of a cliff above the strandline on a Scottish beach. Huge numbers of cocoons were among the seaweed below the cliff. I doubt it's possible to ID the species from photos, but they could well be Coleopa frigida which I think is the commonest Uk species and the leg colours and other features look right, but I don't know how to be sure.