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Blue-winged Olives

Tiny Baetis mayflies are perhaps the most commonly encountered and imitated by anglers on all American trout streams due to their great abundance, widespread distribution, and trout-friendly emergence habits.

Mayfly Species Caudatella columbiella

Taxonomic History

This species was previously considered synonymous with the more common Caudatella heterocaudata, but it was given the status of a separate species by Taxonomic Review of the Caudatella heterocaudata (McDunnough) and C. hystrix (Traver) Complexes (Insecta: Ephemeroptera: Ephemerellidae).

Physical description

Most of these descriptions are direct quotes from the original scientific sources describing or updating the species, although there may be errors in copying them to this website. Such descriptions aren't always definitive, because species often turn out to be more variable than the original describers observed. In some cases only a single specimen was described. However, they are useful starting points.


Described by Jacobus 2010 (2010)

Similar to Caudatella heterocaudata, but different in that Caudatella columbiella has paired medial spines on abdominal tergum 1, the other paired medial spines sharp at the tips, and cerci that are approximately one-sixth the length of the median filament, or about one-half the length of the abdomen.

Male Spinner

Described by Jacobus 2010 (2010)
Wing length: 6 mm

Similar to Caudatella heterocaudata, but different in that male adults of Caudatella columbiella (forewing length ca. 6 mm) are smaller than those of Caudatella heterocaudata (forewing length at least 7mm), and Caudatella columbiella male adults usually have abdominal maculation that is not as highly contrasted from the base coloration.

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