Sialis

Classification

Phylum: Arthropoda
Subphylum: Hexapoda
Class: Insecta
Order: Megaloptera
Family: Sialidae
Genus: Sialis

Pronunciation

How to pronounce Sialis: /ˈsaɪælɪs/

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Summary

Sialis is a genus of alderflies in the family Sialidae, known for their aquatic larvae and distinctive wing structure. They are primarily found in riparian habitats and have a life cycle that requires specific waterbody types for their development.

Physical Characteristics

8-18 mm to wingtips; black or dark brown; heavily-veined wings folded roof-like over back; head primarily black and lacking ocelli; antennae roughly half body length; fourth tarsal segment widened with two lobes.

Identification Tips

Identification of many species requires microscopic examination of male genitalia; wings have large cells forming a network, specifically with less than fifteen square cells in Sialis compared to other Megaloptera.

Habitat

Adults typically found on vegetation near larval habitats like streams and ponds; larvae prefer soft substrates (mud, silt, detritus) with plant debris accumulations.

Distribution

Holarctic; found throughout Europe and widespread in parts of North America, especially eastern U.S.

Diet

Larvae prey on aquatic invertebrates (chironomids, tubificid worms, ostracods); adults eat little, if at all.

Life Cycle

Typically May to June in most places, with variations depending on region; larvae overwinter; pupation occurs above water level.

Reproduction

Mating occurs at night; females lay up to 2000 eggs in groups of about 200 on the leaves of shore plants, and larvae fall directly into the water upon hatching.

Ecosystem Role

As larvae, they feed on a variety of aquatic invertebrates; their presence can indicate healthy water systems.