Mayfly Species Baetis rusticans (BWOs)

Abdominal tergites 2-6 of male imago olive brown, the posterior margins deeper ruddy brown; genitalia of the Baetis intercalaris type, the tubercle on the inner apical margin of the first forceps joint well developed.

Turbinate eyes moderate, red-brown. Head and thorax deep olive brown. Anterolateral margins of the mesonotum paler, “at times terminating in a small yellowish spot on each side of the anterior tubercle”; posterior portion of mesonotum with lateral and central tinges of ruddy brown, the scutellum sometimes paler. Ochreous markings on the pleura. Anterior projection of metanotum whitish. Legs pale yellowish brown; femora, especially near the apex, tinged with deeper brown. Wings hyaline, cross veins slightly brown-tinged. Cross veins of the stigmatic area of the fore wing 4-6 in number, with slight granulations between them. First pair of intercalaries short or obsolescent, second pair shorter than the third. Hind wing about two and one-half times as long as its width; third vein extends weakly to the middle of the hind margin, at the base bent strongly toward vein 2. No intercalaries.

Abdominal tergites 2-6 semi-translucent, olive brown, the posterior margins narrowly deeper, ruddier brown; 7-10 opaque russet brown. Sternites 2-6 smoky hyaline; 7-9 whitish with brown tinges, the posterior margins edged with reddish brown. Tracheae of the stigmatic area form a black lateral line. Tails and forceps whitish. The tubercle on the inner apical margin of the first forceps joint is well developed.

Distinguished from B. levitans (now a synonym of Baetis flavistriga) by the better development of the tubercle on the first forceps joint, and the much darker abdomen. The smaller size, and lack of intercalaries in the hind wing, separate it from Baetis brunneicolor .