Alder fly

Sialis

The Alder fly is a slow-moving insect commonly found on plants near Hainault Lake. Its carnivorous larvae live in silt on the lake bottom. Adults emerge in large numbers in early summer. They have a short lifespans of only a few days, during which they mate. Mating occurs at night, and females deposit their eggs on overhanging vegetation. The larvae then hatch and fall into the water, where they develop over one or two years.