Small black flies

Small black flies

Observation - Small black flies. Description: Small black 'flies' gathered in 10s of thousands on long grasses and now on a small Acer. We've seen these in large numbers since at least early July. Length 5-6 mm

Small black 'flies' gathered in 10s of thousands on long grasses and now on a small Acer. We've seen these in large numbers since at least early July.
Length 5-6 mm