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Alderfly

Alderflies are megalopteran insects of the family Sialidae. They are closely related to the dobsonflies and fishflies as well as to the prehistoric Euchauliodidae. All living alderflies – about 66 species all together – are part of the subfamily Sialinae, which contains nine extant genera.

Description

Sialinae have a body length of less than 25 mm (1 inch), long filamentous antennae, and four large dark wings of which the anterior pair is slightly longer than the posterior. They lack ocelli and their fourth tarsal segment is dilated and deeply bilobed. Dead alderfly larvae are used as bait in fishing.

Life cycle

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 larvae are aquatic, active, armed with strong sharp mandibles, and breathe by means of seven pairs of abdominal branchial filaments. When full sized, which takes between one and two years, they leave the water and spend a quiescent pupal stage on the land before metamorphosis into the sexually mature insect. Adult alderflies stay near to the water in which they had lived when they were younger. Once in their adult stage, they tend to live only 2 to 3 weeks, which they spend mainly in reproducing.

Classification

In addition to the nine living genera, there are several genera of fossil alderflies.

Family Sialidae

Sialis lutaria is the commonest alderfly in the United Kingdom and across much of Europe.

References

External links