viridula adults are large green shield bugs, approxomately 15 x 8 mm in size.
The instars can be differentiated from one another by colour and size variation ( Kobayashi, 1959). By the fifth instar, a considerable proportion of each is green. On hatching, the nymphs are mostly black. Nymphal colour changes progressively in successive instars. Nymphs have no wings, but wing pads are visible on fifth-instar nymphs. Adults were thought to have five (hence the name Pentatomidae), but recent investigations show that the second antennal segment has a false division ( Jeram and Pabst, 1996). The antennae of nymphs have four segments. The head of the developing embryo becomes visible 3 days after oviposition, as a red crescent. As they develop they become deep yellow, then pinkish, and finally bright orange. Eggs are cream to yellow, slightly elongate, and circular from above. Each egg is tightly glued against other eggs and to the substrate, with no intervening gaps. The general appearance and size of the eggs, five nymphal instars and adults of each sex has been detailed by Drake (1920) and Corpuz (1969) and outlined by Todd and Herzog (1980) and Todd (1989).Įggs are deposited in tightly packed, single-layered rafts of about 60 (range of 30-130) eggs ( Van den Berg et al., 1995). viridula ( Jeraj and Walter, 1998), but what this means for pest management remains unclear. cryptic or sibling species) is included under the single name N. Indications have emerged that more than one species (i.e. Ironically, Linnaeus' type specimen was a red colour form ( Freeman, 1940), which explains why the green bugs are sometimes given only varietal status. The green variety is the usual colour form of the species. Other varietal names that have been used are dealt with by Hokkanen (1986). aurantiaca (golden) appear in the literature, although they have no formal taxonomic standing ( DeWitt and Godfrey, 1972). viridula (green vegetable bug) forms were originally described as species in their own right, so the names N. Several such forms have been described, with about 10 in Nezara viridula ( Hokkanen, 1986).
Species in the genus have various colour forms. Todd and Herzog's (1980) review has a key to the stink bugs in North American soyabeans. Freeman's (1940) revision of the genus Nezara provides an accessible review of the nomenclatural history of the species, which has since remained stable.