Aphids moult four times before reaching adulthood. With each moult they shed white skin, betraying their presence in the crop.
Reproduction of the mottled arum aphid is entirely by parthenogenesis, with unfertilized viviparous females continuously producing new generations of females. There is no sexual stage in the life cycle.
Wingless females of the mottled arum aphid are shiny whitish, yellowish or green with black cross bands behind the head, broken along the midline, and a large horseshoe-shaped spot on the back of the abdomen. These black markings can be highly variable. Adult females are 1.2-2.6 mm long. Immature Neomyzus circumflexus are usually the same background colour as their parents, but they lack the characteristic black markings.