Nezara viridula
In 2015, the southern green stink bug was reported south of Seattle near Seattle University and Seward Park. This stink bug was abundant and already reached populations damaging to cherries and raspberries. Their abundance suggests that they may have been in the area for several years.
Pest description and damage Southern green stink bug (SGSB) adults are green, usually with three light dots along the front edge of the triangular pronotum. There are several color variations of this species and sometimes the overwintering adult will change to brown, then back to green in spring. Usually among the adult stink bugs, there will be distinctive patterned nymphs sporting black and white or green and white spots. SGSB can be confused with the more common green stink bug (GSB), but GSB nymphs do not have the distinctive spots. Eggs are laid in clusters of about 20-30 eggs each. If you are not sure of the ID, samples can be photographed and submitted to the mapping website [see insert] or taken to county Master Gardener clinics or to local Extension offices. Damage depends on the plant part attacked and can include wilting buds, tar spots on fruit or leaves, honeydew or sooty mold, fruit with cat-facing, sunken areas, or dark corky areas within. These stink bugs can become a nuisance when they overwinter in homes, but they do not reproduce in households nor do they bite people. All stages emit a repugnant odor, which smells a bit like bleach.
Biology and life cycle The southern green stink bug adults overwinter under bark, in leaf litter, or more notably in house walls, attics and other protected areas. As soon as the spring weather warms, they emerge and start laying eggs. Eggs hatch in five days to three weeks depending on temperature. The first nymphs look like small dark dots and cluster on the eggs for protection. They do not feed until they molt to the second instar a few days later. There are five instars, each taking about 5-7 days to develop. Each instar is distinctly colored with black and white spots. The fifth and final instar will have visible wing buds, a warning that the next stage will be green egg-laying adults. In warmer climates, there are up to four generations a year.
Pest monitoring Several traps are available on the market for commercial growers and homeowners. For small-scale trapping, an aluminum turkey pan with a half-gallon of water and a bit of detergent soap placed under an incandescent light at night is effective. A variety of pheromone traps can be used to monitor this stink bug species. Sweeping with a net may be useful in shrubbery and low hanging tree branches. Beating vegetation (including perimeter weeds), bushes, or branches to dislodge both adults and nymphs over a large tray or light-colored sheet. When autumn arrives, check the south and west side of the home for aggregating stink bug adults. They will work their way inside the home as it gets colder.
Management—cultural control
During late autumn, remove landscape weeds and plant debris where stink bugs will overwinter. Trap crops, such as beans, can attract stink bugs. Consider planting perimeter rows of a trap crop in early spring. Later in the spring, destroy the trap crop when stink bugs are found.
Management—physical control
Remove home-invading stink bugs by hand or with a shop vac. In late autumn or early spring, vacuum aggregating masses from the house siding. Captured bugs should be killed (freezing is recommended) otherwise they may find their way back to host plants. Keep stink bugs out of the home by caulking and sealing all cracks and crevices around doors, windows, faucets and wires. Screen attic, soffit and crawl space vents and windows. Remove, or screen window air conditioners where they get in most easily. Use a well-sealed floating row cover to prevent stink bugs from settling on shorter crops.
Management—biological control
Seventy-one parasitoids are known worldwide and there are many stink bug predators. As with any invasive pest, it is likely that outbreak conditions will exist for a few years, before natural enemies will begin to take their toll and pest numbers will drop to manageable levels.
For Management—chemical control
See “True bug” in Table 1:
Chemical Control of Landscape Pests
For further information:
See “Stink bug” in:
CABI (Centre for Agriculture and Biosciences). 2016. Nezara viridula (green stink bug). https://www.cabidigitallibrary.org/doi/10.1079/cabicompendium.36282
Looney C., M. Tilbury, B. Carman, T. Murray and M. R. Bush. 2019. An Established Population of the Southern Green Stink Bug, Nezara viridula (Linnaeus), in Washington State. Proceedings of the Entomological Society of Washington 16, December 2019.