Mayfly Species Baetis piscatoris (BWOs)

Abdominal tergites 2-6 of, male imago yellowish hyaline, a purplish red band on posterior margin of each; genitalia of the moffati type (now a synonym of Baetis tricaudatus).

Head and antennae reddish brown. Turbinate eyes moderate in size, on a rather high stalk; stalk yellowish, upper surface light orange, in alcoholic specimens. Thorax rather dark reddish brown; a yellowish streak on mesonotum anterior to wing root, another along postero-lateral margin; a small yellow area anterior to the scutellum; margins of scutellum blackish. Intersegmental areas of pleura yellowish red. Fore legs light yellowish brown; middle and hind legs yellowish, joinings and tips of tarsi light brown. Wings hyaline, venation pale; longitudinal veins of costal margin faintly yellowish. A faint whitish cloud in stigmatic area of fore wing; 8-11 cross veins, aslant, sometimes incomplete, occasionally anastomosed; with granulations between them. Intercalaries of the first and second interspaces may be single or paired; shorter than the following pairs. Hind wing rather large; three longitudinal veins; costal projection well developed. Usually traces at least of two intercalaries between the 2nd and 3rd veins; often also a faint intercalary between veins 1 and 2.

Abdominal tergites 2-6 yellowish, hyaline; on the posterior margin of each is a prominent purplish-red band, not extending to the spiracular line. Tergite 2 is often slightly tinged with brownish. Sternites 2-6 paler yellowish. Spiracular area outlined by a geminate purplish line, from which on each segment arise lateral branches to tergite and sternite. Segments 7-10 opaque, light reddish brown, the margins narrowly darker; sternites only slightly paler than tergites. Tails pale yellowish brown, paler at tips. Forceps yellowish.

In type of genitalia, this species is allied to the pale B. lasallei (now a synonym of Baetis intercalaris) and to the yellowish-brown Baetis adonis, from both of which it may be distinguished by the prominently banded abdomen; other species having the same type of abdomen are darker in coloration (Baetis tricaudatus, of the color of which we are not certain, is a larger species). B. cingulatus (now a synonym of Baetis phoebus), which has a similarly-marked abdomen, has genitalia of the Baetis intercalaris type.

Female reddish or orange-brown; legs yellowish brown, tarsi somewhat darker. Venation light reddish brown. Abdominal sternites yellowish; tergites banded as in male. Spiracular markings prominent. Tails as in male.