The Banded Dark Fishfly: Nigronia fasciata

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June 19, 2025, 3:35 pm EDT | 1 minute read

The Banded Dark Fishfly: Nigronia fasciata

The banded dark fishfly, scientifically known as Nigronia fasciata, is a member of the family Corydalidae within the order Megaloptera. Here is a detailed account:

Physical Characteristics: The body length of females ranges from 23 to 30 mm, while that of males is 10 to 25 mm, and the larvae are 26 to 33 mm long1. The wings are dark brown, featuring an off - white stripe across the middle that extends from the outer edge (costa) to just before the inner wing margin. This stripe is always spotted with several brown patches, especially on its basal half, and also has a dip at the center of its base margin1. There is a small off - white patch on the outer edge near the wing tip, along with some white flecks1. The hind wings also have an off - white stripe in the middle, with white at the base and white flecks on the lower half1.
Habitat and Distribution: The larvae of the banded dark fishfly inhabit small streams that have sandy bottoms, few rocks, and good water quality1. In terms of distribution, it is found in the eastern United States, reported from 23 states but not from the upper Midwest, and is absent in Canada1.
Life Cycle and Behavior: From May to early June, females lay large egg masses on the underside of leaves of branches overhanging streams1. After hatching in about 14 days, the larvae drop into the water and feed mainly on isopods and caddisflies, and may even resort to cannibalism1. As adults, they may feed on nectar and drink sugar water in the laboratory1.

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