Mayfly Species Isonychia campestris (Slate Drakes)

Somewhat paler than Isonychia sicca; venation dark.

Head of female pale yellowish, with traces, more or less distinct, of brown submedian stripes on the vertex and occiput. Blackish brown spot between eye and lateral ocellus, but no dark mark in corners of occiput. Thorax of male light brown, shaded somewhat with reddish and blackish brown on the scutellum. Fore leg entirely reddish black, tarsi somewhat paler. Middle and hind legs dull yellow, with slight red shading on the femora. Wings with fine veins, all dark-tinged.

Abdomen dorsally dull brown tinged with red, shaded laterally with deeper brown in the form of poorly defined dark patches; lateral margin pale brown. Light brown ventrally, rather paler than the dorsum. Penes similar in form to those of sicca.

Head of female pale yellowish, with traces, more or less distinct, of brown submedian stripes on the vertex and occiput. Subanal plate of female rather deeply excavated apically, its outer angles acute.