‘Like the flip of a switch, it’s gone’: Has the ecosystem of Ireland's largest lake collapsed?

Lough Neagh’s flies were seen as a nuisance. Now their sudden disappearance is a startling omen for a lake that supplies 40% of Northern Ireland’s water

Algae on the surface of Lough Neagh at Ballyronan Marina in September 2023. Picture: PA Images

Declan Coney, a former eel fisher, knew there was something wrong when the famed swarms of Lough Neagh flies failed to materialise. In past years, they would appear around the Northern Irish lake in thick plumes and “wisps” — sometimes prompting mistaken alarm of a fire incident, Lough Shore residents say.

Clothes left out on a washing line “would be covered in them”, Coney says. So would any windshield on a vehicle travelling around the lough’s 90-mile shoreline. Conservationists marvelled at their courtship dances, hovering above treetops.