Mayfly Species Caenis hilaris (Angler's Curses)

A small species with short forceps; mesonotum pale yellowish; head whitish.

Head of female whitish, of male sometimes shaded with light purplish red; eyes black, ocelli pale with black basal rings; antennae slightly smoky beyond the basal joint. Pronotum whitish; antero-lateral margins may be tinged with blackish; near the posterior margin are two small black dots, one on each side of the median line. Mesonotum pale yellowish; a faint blackish V-mark anterior to the scutellum. Pleura pale, with some short blackish streaks at the bases of the legs and the wing roots. Sternum pale. Legs white; fore femora shaded with smoky apically, fore tibiae faintly smoky; tibia twice the length of the femur, tarsus shorter than tibia. On the dorsal edge of each femur near the apex is a fine short black streak. Wings semi-hyaline whitish, subcosta and radius purplish black for most of their length.

Abdomen whitish. Tergites 1 and 2 shaded faintly with blackish; a fine short blackish streak laterally on the margins of segments 7-9. Sternites white, unmarked. Forceps and tails whitish. Forceps short, narrowed evenly toward the tip; the forceps base covers most of the penes (see Pl. XXXIX).

The spiracular streaks on segments 7-9 only, distinguish this species from others allied to it; the dark femoral dashes separate it from C. ridens (now a synonym of Amercaenis ridens), and the paler mesonotum and slight shading on tergites 1 and 2 separate it from Caenis anceps.