Sialis lutaria

Sialis lutaria is a species of alderfly belonging to the order Megaloptera family Sialidae.

This species is mainly present in Austria, Belgium, United Kingdom, Czech Republic, France, Germany, Italy, Spain, Poland, Romania and Switzerland.

They have a stocky body with a black or dark brown basic coloration, including head and legs. The wings are greyish, membranous and translucent, with pronounced dark venation. At rest they are held roof-like over their body. Adults can reach 20 millimetres (0.79 in) of length and are most often encountered from May through June on vegetation near slow-flowing streams or close to ponds.