Mayfly Species Drunella lata (Small Blue-Winged Olive)

A species of the fuscata (now a synonym of Drunella walkeri) group; rather closely allied to E. cornutella (now a synonym of Drunella cornutella), from which it may be separated by the more inflated second joint of the forceps, which is likewise rather sharply constricted near the middle.

Head and thorax deep blackish brown. Pleura and lateral areas of the mesosternum shaded with dull olive brown. Fore femur and tibia rather dark brown, about equal in length; coxa rather olive brown; tarsus pale, whitish. Middle and hind legs paler, the femora pale olive brown, the tibiae and tarsi lighter; an indistinct reddish longitudinal streak dorsally on the femora. Hind femur about as long as tibia and tarsus combined. Wings hyaline; venation pale, the main veins of the costal margin tinged with yellow; a small brownish spot at the base of the fore wing. Abdomen somewhat paler blackish brown dorsally, almost unicolorous. Indications of a pale mid-dorsal line on the anterior tergites. Sternites paler, dull olive brown. Second joint of forceps strongly inflated at each end and sharply constricted near the middle; penes united almost to the apex, the apical notch shallow and rounded (see fig. 153). Tails dull whitish.

Nymph brownish black; prothorax and 8th tergite usually conspicuously white, but the amount of pale color seems to be variable. Frontal horns present but very short, not reaching to the margin of the frontal shelf. Anterior margin of fore femur with teeth or spines; posterior margin rather widely expended. Tibial ‘thumb’ stout, almost straight, extending about to the middle of the tarsus. No dorsal spines (although mentioned in the original description, the type material and all other specimens examined show no such spines). Tails light brown; basal joinings dark brown.