About Halyomorpha halys (Stål, 1855)
Adults of Halyomorpha halys, the brown marmorated stink bug, are roughly 1.7 cm (0.67 in) long and about equally as wide, taking the characteristic heraldic shield shape of bugs in the superfamily Pentatomoidea. When viewed from above, their upper body is generally dark brown, while their underside is creamy white-brown. Individual coloration can vary: some specimens display different shades of red, grey, light brown, copper, or black. The name "marmorated" means variegated or veined like marble, which describes the markings of this species. These markings include alternating light-colored bands on the antennae and alternating dark bands along the thin outer edge of the abdomen. The brown legs have faint white mottling or banding. Nymph stages are black or very dark brown, with red integument between the sclerites. First instar nymphs have no white markings, while second to fifth instar nymphs have black antennae with one white band. Nymph legs are black with white banding that varies in amount. Freshly molted individuals of all life stages are pale white with red markings. Eggs are typically laid in masses of 28 on the undersides of leaves; they are light green when first laid, and gradually turn white over time. Like all stink bugs, Halyomorpha halys has glands that produce its defensive smelly chemicals on the underside of the thorax, between the first and second pairs of legs.
