SOUTHERN GREEN STINK BUG: Nezara viridula, Pentatomidae

ADULT: They are light to medium green, shield-shaped bugs, 1/2 to 2/3 in. long with reddish bands on their antennae. A rounded spine on the second abdominal segment points slightly forward between the bases of the hind legs.

EGG: The barrel-shaped, pale yellow (becoming green), 1/16 in. tall eggs are deposited under leaves and arranged very tightly in a series of rows with 10 to 50 eggs per mass. Nymphs emerge in 6 to 14 d.

NYMPH: They pass through five nymphal instars taking from 23 to 60 d depending on temperature. First instars are reddish-black to black and tend to remain clustered around the eggs without feeding. Second instars are black with faint white spots on the top of the abdomen. They begin to feed on plant tissue around the egg mass. Third instars are usually similar to seconds, but are occasionally green with pinkish-red markings. They disperse from the egg mass as a group. The last two instars are light green with pink and black markings and white spots. Green wingpads extend back from the pronotum on the back in the fifth instar. There is no pupal stage in pentatomids.

GENERATION TIME: 29 to 74 d.

DAMAGE: Stink bugs are greater pests in central and northern Florida than in south Florida, where most production is completed before these stink bugs become common. Stink bugs feed by puncturing plant tissue and sucking out plant fluids. Feeding punctures into the whorl result in leaves with rows of star shaped punctures across expanding leaves. Punctures into region of the stalk from which the ears develop result in aborted or mal-formed ears with poor husk coverage. Kernels are punctured through the husks causing them to become sunken or to pop open. Ear feeding can also lead to a higher incidence of corn smut.  Injured kernels become infected with fungus. Large populations can appear quickly in fields due to male aggregation pheromones. Considerable damage can occur in fields with these aggregations.

CONTROL: Populations can be clumped in fields due to their aggregative nature during early instars.  Spot or edge treatments with pesticides may be enough to prevent economic damage.  Treatment thresholds are available for field corn during ear stage.  These suggest application of foliar sprays when density of nymphs greater than 1/4 in. long reaches one per five plants during early silking through milk stage.  Higher densities of one per plant are suggested for the period from early milk through hard dough stage.  Due to consumer expectations and shelf life concerns, thresholds would be lower in sweet corn to prevent economic losses.  Pesticides are available for post-emergence foliar application. Formulations, rates, and pre-harvest intervals of insecticides labeled for stink bug control in Florida are listed below for sweet corn (Table 1) and field corn (Table 2).