A Mayfly - Hexagenia limbata
These large tusked, burrowing mayflies as larvae, prefer soft-benthic sediments of slow large river depositional areas or lake bottoms. They come off in large numbers (swarms) about mid-July from Flathead Lake, Whitefish Lake and a few other lakes in Northwest MT.
Tusks that curve upwards and the frontal process of the head is rounded instead of forked, seperates this genus from the other Ephemerid genus, Ephemera that is found in Montana, and distinguishes it from the genus Ephoron in the Family Polymitarcyidae whose tusks curve downward.
Observations in Montana Natural Heritage Program Database
Number of Observations:
(Click on the following maps and charts to see full sized version)
Map Help and Descriptions
(Observations spanning multiple months or years are excluded from time charts)
- Additional Sources of Information Related to "Insects"