alderfly

[ awl-der-flahy ]
/ ˈɔl dərˌflaɪ /

noun, plural al·der·flies.

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

Origin of alderfly

First recorded in 1820–30; alder + fly2

British Dictionary definitions for alder fly

alder fly

noun

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