Deepwater Mayfly
Photo is not the species of interest but rather a representative specimen of the family Heptageniidae. Photo credit to Valley City State University
A member of the family Heptageniidae, the flat headed mayflies. The larval stage has a flattened body shape and head. Typically, the lateral margin of the head is visible behind the eyes. They are primarily found in the sand dominated (psammophilous) river and stream systems within the Missouri River drainage of western North Dakota and eastern Montana. Larval stage present throughout the open water season but most abundant through July-August when they typically emerge into the adult stage
Status in North Dakota
Year-round resident of North Dakota waterbodies in the larval stage with a short-lived adult form following emergence.
Range Map
Deepwater mayfly potential range in North Dakota.
Reason for SWAP Designation
A Midwest regional species of concern with limited data in North Dakota and an at-risk species based on expert review (SGCN c).
Documented in Billings, Bowman, Dunn, McKenzie, Morton, and Slope counties but is likely present in other areas of western North Dakota.
Raptoheptagenia cruentata is considered a species of concern in Montana.
They can be locally abundant in suitable habitat, but limited or declining records create large-scale population concerns across much of its range.
Threats
Limited habitat availability, land development, climate change, sedimentation, energy development, agricultural practices and habitat modification and inundation due to damming of river systems.
Research and Monitoring
Limited research has been conducted.
The North Dakota Department of Environmental Quality (NDDEQ) conducts biological monitoring surveys on State waters as part of their Index of Biotic Integrity (IBI) development.
Additionally, a monitoring protocol for aquatic invertebrates is being developed by the North Dakota Game and Fish Department (NDGF) under the State Wildlife Grant Program with implementation as a future goal.
Additionally, a survey of aquatic invertebrates in cooperation with Valley City State University is currently underway to gain additional baseline information on SGCN’s.
Management Recommendations
- Protect and conserve large, intact tracks of native/unbroken forested areas.
- Develop/maintain buffers along riparian areas.
- Partner with local, state, and federal entities to limit chemical use in/near aquatic habitats.
- Partner with local, state, and federal entities to remove dams where logically feasible.
- Encourage efficient use of pesticides.
Primary Geological Regions
Habitat Associations
Habitat Use
Occurs in large sand dominated river systems such as the Missouri River and Little Missouri River.