Sialis lutaria
Sialis lutaria is dark brown to black in colour. It has four membranous wings all unpatterned, uniformly brown in colour with dark veins. Its wings are held roof-like over its abdomen. The antennae are shorter than the forewings. It has a body length of 10mm and a wingspan of 22-30mm.
This is the commonest species of megalopteran in the British Isles, found throughout England, Scotland and Wales, but apparently local in Ireland.
To identify to species level you must examine the genitalia.
Male genitalia: Tip of abdomen hinged (in vertical plane) opening up to reveal genital structures. Genital structures as in figure, the Subgenital plate extends to or past the tip of the abdomen in the lateral view.
Female genitalia: Tip of abdomen is rounded, without an opening. When viewed on the underside (ventral view) the Anal plate has a distinct shape with a “square” edge.
Still and flowing waters, ranging from small ponds, large lakes and rivers. Larvae aquatic.