A female will lay up to 700 eggs on the surface of knotweed leaves and stems during her lifetime. Eggs hatch after approximately 12 days, and the nymphs pass through five instars before becoming adults. All stages feed on the leaves and stems of knotweed by inserting their mouthparts and removing the sap. While feeding, nymphs excrete lerp, crystallized honeydew that is conspicuous as white strings and flakes on the plant surfaces. Nymphs typically only move short distances on the plant surface, often seeking out the more sheltered locations on the plant, such as under leaf sheaths or inside of leaf curls. Adult A. itadori are winged, flight-capable, and quite mobile. Only the adult stage overwinters. In late summer, in response to shortening day lengths, adults will enter a state of dormancy (diapause) and will seek out safe overwintering sites, such as under the bark of adjacent trees or in old knotweed stems. During this state, they neither feed nor reproduce. Adults that are entering diapause will turn distinctly darker in color with the brown patches on the wings appearing black. These are referred to as winter morph adults. In most areas within the invasive range of knotweeds, two generations are likely to be supported, though some southern locations could have up to three.