Abstract
Adults of alderflies (Sialidae) have a body length of less than 25 mm, long filamentous antennae, and four large dark wings of which the anterior pair is slightly longer than the posterior. The females lay a vast number of eggs on grass stems near water.
When the larvae are born they drop into the water or the ground nearby it and make their way into their new aquatic biome. The aquatic larvae are flat bodied and cryptic in color.
Sialis larvae are found in many habitats, ranging from small springs to large rivers and ponds. They usually occur where the substrate is soft and where dead leaves and other detritus have accumulated.
Larvae may dig into the substrates to a depth of several centimeters. The larvae are active, armed with strong sharp mandibles, and breathe by means of seven pairs of abdominal branchial filaments (tracheal gills).
At the and of abdomen is located long tapered median filament that is covered with long hair-like sensilla, which are used to detect external stimuli. Larvae crawl along the bottom, they are non-selective predators that feed on insect larvae, anneliid worms, crustaceans and molluscs.
Cannibalism can occur if population density in an area is high. Pupae are found on the land in soil and moss.
Alderfly pupae are exarate, meaning that the developing wings, legs, antennae and mouthparts are attached only at the base end and do not develop in a cocoon. This contribution describes the conditions for rearing larvae of alderflies and some ideas for experiments and observations in a school aquarium.