alder fly

noun, plural al·der·flies.

1. any of several dark-colored neuropterous insects of the family Sialidae, the larvae of which are aquatic and predacious on other aquatic insects.

noun

1. any of various neuropterous insects of the widely distributed group Sialoidea, such as Sialis lutaria, that have large broad-based hind wings, produce aquatic larvae, and occur near water