Length 6-8 mm (Dairella latissima 2). Head shorter than first 3 pereonites combined. P V and VI subequal (Dairella latissima 1). ART 2 of P V longer, than ART 5, ART 6 twice as short as ART 5. UR III with broad rami. In live animals body transparent, with separate brown-violet pigment cells. Ectoparasites on gelatinous plankton. In nature, individuals on hosts tuck pleon under flat pereon. In such a pose they resemble land louse-flies of the Hippoboscidae, ectoparasites of large animals.