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Article written by Calvin R. Fremling regarding cause and coordination of mass emergences of mayflies along the Mississippi River, over a 12-year period of study. Abstract: "The burrowing mayfly (Hexagenia bilineata Say) was reported to be abundant along the Upper Mississippi River as early as 1863 by Walsh and 1890 by Garman. Their abundance, however, has apparently been increased by the construction of 27 navigation dams along the Upper Mississippi River between Minneapolis, Minnesota, and St. Louis, Missouri, Most of the dams were constructed during the 1930's. The silted impoundments afford excellent H. bilineata habitat and the insects often cause severe nuisance problems in river cities (Fremling 1968). The biology of H. bilineata has been reviewed by Needham, Traver & Hsu (1935) and by Fremling (1960). Earlier workers (Needham 1920, Coker 1929) observed that mass emergences of H. bilineata often encompassed large expanses of the river. In an effort to discover the factors which coordinate the mass emergences, specimen vials and collecting instructions were distributed to ship captains, lock masters and other cooperators during the years 1957-1968. Over 1,000 mass emergences have been reported during the 12-year study period. The data indicate (Figs. 1, 2) that H. bilineata apparently emerge en masse along most of the Upper Mississippi River at intervals of 6-11 days and that a single mass emergence often occurs coincidentally along a 1000-km expanse of river. The aforementioned pattern of emergence is not as obvious every year as it was in 1960 and 1963, but similar results have been reported for the years 1958 and 1966 (Fremling 1964, 1968)." Article part of International Association of Theoretical and Applied Limnology / Verhandlungen - Proceedings - Travaux (Verhandlungen des Internationalen Verein Limnologie / Verh. Internat. Verein Limnol.), Congress in USSR 1971, volume 18, December 1973. 7 pages. Part of the Cal R. Fremling Collection.

Publication Date


Item Type





Winona, Minnesota


Biologists; Insects Behavior; Mayflies


Special Collections-Library



Rights Management

Requests to reproduce this image must be granted by the Winona County Historical Society.

Contributing Institution

Winona County History Center

Master File Format


Fiscal Sponsor

This project has been financed in part with funds provided by the State of Minnesota from the Arts and Cultural Heritage Fund through the Minnesota Historical Society.

Scanning Responsibility

Northern Micrographics

Date Digital

2019-06-24 00:00

Metadata Creation Responsibility

Anna Gaffey

Unique Identifier


Environmental synchronization of mass Hexagenia bilineata (ephemeroptera) emergences from the Mississippi River



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