I found this specimen in the river at proctor lake. The split tail was a key feature to the bicaudatis specie. The distinct appendages on either side were also key to identifying the specimen.
Citation: Bartis bicaudatis of Gunnison County, Colorado
Small (4 or 5 mm), dark grey/olive body, grey wings, 2 tails.
This minnow mayfly nymph (Baetidae) was found in the littoral zone of a pond in the wetlands of Proctor Lake. This organism was in water approximately six inches deep and abundant with aquatic plants, algae, and terrestrial plant debris.
Minnow mayflies, during the nymph stage, are small, streamlined larvae that possess long antennae, usually 2-3 times the length of the head's width. The head is vertically oriented. Hind wing pads are usually very small, if present at all. Oval shaped gills protrude laterally from the abdominal segments. Either two or three tails are present on minnow mayfly nymphs. When mature, they range in size from 3-12 millimeters ("Order Ephemeroptera - The Small Minnow Mayflies" Digital Key to the Aquatic Insects of North Dakota. Valley City State University, n.d. Web. 12 Nov. 2016.).
Minnow mayflies are found throughout North America and worldwide in lentic and lotic aquatic habitats. These mayflies are very sensitive to pollution, so they require clean, well-oxygenated water. Nymphs feed on dead organic matter and adult mayflies do not possess mouthparts. Minnow mayfly nymphs and adults serve as a primary food source for fish and other aquatic organisms ("Order Ephemeroptera - Mayflies." Bug Guide. Iowa State University, n.d. Web. 12 Nov. 2016.).
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Baetidae is a family of mayflies with about 900 described species distributed worldwide. These are among the smallest of mayflies, adults rarely exceeding 10 mm in length excluding the two long slender tails and sometimes much smaller, and members of the family are often referred to as small mayflies or small minnow mayflies. Most species have long oval forewings with very few cross veins (see Comstock-Needham system) but the hindwings are usually very small or even...