Mayfly - Cinygmula gartrelli ( Cinygmula gartrelli )

Category: Arthropods
Common names: Gartrelli's flat-headed mayfly
Ecosystems: Riparian areas
Vulnerability to climate change (More details)


The population size of Cinygmula gartrelli is low and the trend unknown. These mayfly species are generally rare and have very restricted distributions.

Mayflies are very sensitive to pollution, and as such are usually only found at high quality, minimally polluted sites. Mayflies are a commonly used index of water quality and aquatic ecosystem health.

Description and Range

Physical description

Adult mayflies are delicate and short-lived. They have large triangular-shaped front wings that typically have many veins and are held straight above the body while at rest; the hind wings are small and rounded or may be absent. They have well-developed eyes and small antennae, and their front legs are usually longest. The long abdomen ends two or three long thread-like tails.

Ecology and life history

This species was found at high-altitude creeks, falls, and rivers in Mt. Rainier National Park.

All mayflies are aquatic in their developmental stages. Their lifespan is spent almost entirely undergoing numerous molts.

Larval existence is usually three to six months but can be as short as two weeks or as long as two years. The nymphs are generalists, moving over stones and weeds to graze off bacteria, collecting from sediments or feeding on detritus. Adults do not eat; they have nonfunctional digestive systems.

Unlike most insects, the mayfly typically has two winged stages. It is the only existing insect that molts after getting functional wings. The first stage, the subimago, is a subadult stage typically found perched on shoreline vegetation; it lasts from four minutes to 48 hours (correlated with the lifespan of the species’ adult stage). Soon after it is formed (in most species), the subimago molts to form the imago, the true adult or reproductive stage. Both subimagos and adults tend to remain along banks at emergence sites.

Mayfly eggs are eaten by snails and caddisfly larvae. The nymphs may be eaten by fish, frogs, birds, flies, or water beetles. The subimagos are eaten by fish, birds, dragonflies, water beetles, or other predatory insects.

Mating occurs in a swarm, and the eggs are laid as the female skims the water. The eggs sink to the bottom, and develop sticky substances or adhesive disks, depending on the species.

Adults of most species are short-lived (less than two hours to three days).

Mayfly dispersal is limited in the larval stage by drainage systems and in adult stages by relatively short life spans and weak flying ability of gravid females. Dispersal at the population level has been little studied. Adult dispersal ability has not been extensively studied; however, several characteristics appear to limit occurrences to a short distance, including weak flying ability, extremely short life cycle, and tendency to remain in the area of emergence. Once a population becomes established, there is little opportunity for exchange of genetic materials with populations in other drainage systems.

Geographic range

In Washington, this species occurs in the Ohanapecosh River, Mount Rainier National Park, Lewis County; and Huckleberry Creek and Ipsut Falls in Mt. Rainier National Park, Pierce County. It has also been found in Oregon in the Metolius River, Jefferson County, and in the Flathead and Ravalli counties in western Montana.

For a map of range-wide distribution and conservation status, check out NatureServe Explorer.

Climate vulnerability

Sensitivity to climate change


Little is known about Cinygmula gartrelli, a species of mayfly which has been located in California, Oregon, Washington, Montana, and British Columbia.  In Washington, found in high elevation creeks, falls, rivers in Mt. Rainier NP. All mayflies require aquatic habitats for nymph survival, and this species was located in a river in at least one of the records. Sensitivity likely is tied to this requirement, and the species could be affected by drought, precipitation changes, and summer low flows. Mayflies tend to be sensitive to changes in streambed substrate, water temperature, and water quality as well.

Confidence: Moderate

Exposure to climate change


  • Increased water temperatures
  • Changes in precipitation and/or drought
  • Low summer flows
Confidence: Low


This species is identified as a Species of Greatest Conservation Need (SGCN) under the State Wildlife Action Plan (SWAP). SGCN-classified species include both those with and without legal protection status under the Federal or State Endangered Species programs, as well as game species with low populations. The WDFW SWAP is part of a nationwide effort by all 50 states and five U.S. territories to develop conservation action plans for fish, wildlife and their natural habitats—identifying opportunities for species' recovery before they are imperiled and more limited.

Conservation Threats and Actions Needed

  • Resource information collection needs
    • Threat: Lack of data on current status and distribution
    • Action Needed: Determine distribution and population status
  • Fish and wildlife habitat loss or degradation
    • Threat: Water quality is of extreme importance to aquatic insects
    • Action Needed: Protect riparian habitats
  • Climate and severe weather
    • Threat: Drying of streams
    • Action Needed: Determine distribution and population status

See the Climate vulnerability section for more information about the threats posed by climate change to this species.



Edmunds, G. F. and R. D. Waltz. 1996. Ephemeroptera. Pages 126-163 in R.W. Merritt and K.W. Cummins (editors). An introduction to the aquatic insects of North America. 3 rd Edition. Kendall/Hunt Publishers, Dubuque, Iowa.

Edmunds, G. F., S. L. Jensen, and L. Berner. 1976. The mayflies of North and Central America. University of Minnesota Press, Minneapolis, 330 pages.

McCafferty, W. P. and R. L. Newell. 2007. Insecta, Ephemeroptera: range extension and new state records from far western Montana, U.S.A. Check List, 3(3): 260-261.

Meyer, M. D. and W. P. McCafferty. 2007. Mayflies (Ephemeroptera) of the far western United States. Part I: Washington. Transactions of the American Entomological Society, 133(1-2): 21-63. NatureServe. 2014. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.1. NatureServe, Arlington, Virginia. Available

Meyer, M.D., and W. P. McCafferty. 2007.  Mayflies (Ephemeroptera) of the far western United States. Part 2: Oregon. Transactions of the American Entomological Society 133: 65-114

Other resources