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Alderfly Genus Sialis

Taxonomic Navigation -?-
Kingdom Animalia (Animals)
» Phylum Arthropoda (Arthropods)
» Class Insecta (Insects)
» Order Megaloptera (Hellgrammites, Dobsonflies, and Alderflies)
» Family Sialidae (Alderflies)
» Genus Sialis

24 species aren't included.
Pictures Below
Alderflies are typically mistaken for small hellgrammites as larvae and large caddisflies as adults. They turn up often enough in nymph samples that it's nice to know what they look like. There are rumors of their occasional importance to trout, but the average anglers is not likely to encounter it.  

Where & When

Time Of Year (?): Early season

Hatching Behavior

Time Of Day (?): Evening
Pupae burrow into the ground near to, but not in, the stream. Because the emergence takes place on land it is unimportant to trout.

Egg-Laying Behavior

Time Of Day: Daytime
The mating adults gather over the water in good numbers but do not usually fall into the water unless wind knocks them off course.

They lay their eggs on dry objects near the water. Ernest Schwiebert describes their egg placement in Matching the Hatch:

The egg masses are deposited on rocks, limbs, leaves and bridges where they are over running water and in the sunlight. They are placed so that the hatching larvae fall into the stream.

Larva & Pupa Biology

Current Speed: Slow
Substrate: Silt
The larvae are burrowers like the Ephemeridae mayfly nymphs, digging down into the silt.

4 Alderfly Specimens in the Genus Sialis:

Specimen Page:12
Sialis Alderfly LarvaSialis  Alderfly LarvaView 4 Pictures
Region: Upper Midwest
Collected Feb 5, 2004
Added Jan 25, 2006
Sialis Alderfly LarvaSialis  Alderfly LarvaView 4 Pictures
Region: Upper Midwest
Collected Feb 5, 2004
Added Jan 25, 2006
Sialis Alderfly LarvaSialis  Alderfly LarvaView 3 Pictures
Region: Upper Midwest
Collected Mar 1, 2004
Added Jan 25, 2006
Specimen Page:12

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