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Mayfly Genus Acentrella (Tiny Blue-Winged Olives)

Taxonomic Navigation -?-
» Genus Acentrella (Tiny Blue-Winged Olives)
Species in AcentrellaNumber of SpecimensNumber of Pictures
Acentrella insignificansTiny Blue-Winged Olive00
Acentrella turbidaTiny Blue-Winged Olive00

6 species aren't included.
Common Names
Pictures Below
The only Acentrella species commonly reported to be important to anglers is Acentrella turbida, though Acentrella insignificans is important in some western locales. See the species pages for distribution and timing details. This genus is one of two (including Heterocloeon) that can easily be distinguished from other Baetidae genera by the presence of a conical mesonotal projection (Conical mesonotal projection: small cone shaped spike sticking up from the top and front part of the middle thorax segment.). A. turbida lacks hindwings which is useful for distinguishing this species from all others in either genera. A. turbida was previously known by the names of its synonyms (Synonym: A former name of a taxon, usually a species. Entomologists frequently discover that two insects originally described as different species are one in the same, and they drop one of the names. The dropped name is said to be a synonym of the remaining name. These changes take a while to trickle into the common knowledge of anglers; for example, Baetis vagans is now a synonym of Baetis tricaudatus.) Pseudocloeon turbidum in the West and Pseudocloeon carolina in the East.

Hatching Behavior

Time Of Day (?): Early evening; sometimes all day

The nymphs are normally excellent swimmers, but they become much less mobile as they're emerging and dead-drift (Dead-drift: The manner in which a fly drifts on the water when not moving by itself or by the influence of a line. Trout often prefer dead-drifting prey and imitating the dead-drift in tricky currents is a major challenge of fly fishing.) helplessly to the suface. Considering that they then emerge and fly away quickly, this makes the nymphs the prime stage to match during this emergence.

Spinner Behavior

Time Of Day: Dusk

These species molt into spinners and mate the same day they emerge. The spinner activity usually comes at dusk, or even after dark.

Nymph Biology

Current Speed: Slow to Medium

Substrate: Rocks, logs, gravel, vegetation

Environmental Tolerance: Widely tolerant, but best in cold rivers

Pictures of 7 Mayfly Specimens in the Genus Acentrella:

Specimen Page:12
Female Acentrella (Tiny Blue-Winged Olives) Mayfly DunFemale Acentrella (Tiny Blue-Winged Olives) Mayfly Dun View 3 PicturesI've lost the date information for this specimen and taken a guess.
Collected August 1, 2004 from unknown in Wisconsin
Added to by Troutnut on January 25, 2006
Male Acentrella turbida (Tiny Blue-Winged Olive) Mayfly SpinnerMale Acentrella turbida (Tiny Blue-Winged Olive) Mayfly Spinner View 3 PicturesI would not like to have to match this hatch. These are the smallest mayflies I have ever seen. I used to think Caenis was the smallest adult mayfly in the west but these guys are about 4mm long. The male eyes are two toned, brown above and olive below. The abdomen is dark brown interspersed with light brown. The abdomen is clear for the anterior (Anterior: Toward the front of an organism's body. The phrase "anterior to" means "in front of.") 2/3rd and the remainder is white. The tails are twice as long as the insect. There is only one pair of wings.
Collected July 27, 2011 from the Touchet River in Washington
Added to by Bnewell on July 27, 2011
Specimen Page:12

Recent Discussions of Acentrella

acentrella nymph 22 Replies »
Posted by Goose on Nov 3, 2006
Last reply on Sep 15, 2022 by Wiflyfisher
Hi Jason! Do you have a picture of the (acentrella-miniature BWO nymph) on the site? I've been fishing them and wanted a better idea of how they look.

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