Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hemiptera
Suborder: Heteroptera
Infraorder: Pentatomomorpha
Superfamily: Pentatomoidea
Family: Pentatomidae
Genus: Nezara
Species: N. viridula
Binomial: name Nezara viridula
Common name: Green vegetable bug, Southern green stink bug,

Nezara viridula is native to South Africa and is a pest of vegetables with a wide host range. These plant-feeding bugs are believed to have originated in Ethiopia,  It was first recorded attacking bean crops at New Plymouth in 1944 and is mainly confined to warmer areas of the North and South Islands.
These are green, shield-shaped flattened bugs, 12mm - 15mm long with 3 small spots in a line between the wing insertions. These spots distinguish them from the native green bug (Glaucius amyoti), which lacks the spots.
The Pentatomidae are often called stink bugs because when handled they emit a strong smell. The nymphs have prominent glands on the upper (dorsal) side of their abdomen, while adults have glands between the base of their legs. The chemicals may deter predators and cause other bugs to drop to the ground, but some of the chemicals produced may also act as aggregation pheromones.
Their eggs are cylindrical, about 1mm long, and usually laid in clusters. They are creamy-white in colour when freshly laid but turn reddish close to hatching. The nymphs are orange initially, these later change to black marked with spots of yellow, green and red. The green colour becomes dominant in the last instars, and in the overwintering adults becomes much darker, often with a purplish tinge. Green vegetable bug overwinters as the adult in long grass or other suitable plant covers. Eggs are laid in the spring and hatch after about ten days. The entire lifespan occupies about eight weeks and there are two to three generations a year. Adults may live for three-six months.

Their colour varies it is mostly green, sometimes yellow, orange or brownish hue.
Adult photographed early September
1-Nezara viridula Green Vegetable bug-11.JPG

1-Nezara viridula Green Vegetable bug.JPG

Showing its wings (March)
1-Nezara viridula Green vegetable bug.JPG

1-Nezara viridula Green Vegetable bug-8.JPG

An adult Nezara viridula in cold weather. The scutellum (The triangular shield) with 3 small yellowish spots and a small dark pit at each corner. 
1-Green vegetable bug Nezara viridula 22-06-2018 4-05-16 PM.JPG

1-Green vegetable bug Nezara viridula 22-06-2018 4-06-17 PM.JPG

Another during winter.
Adult Green vegetable bug in cold weather-5.JPG

Underside June.
Nezara viridula Green vegetable bug p.m.-009.JPG

1-Green vegetable bug Nezara viridula 22-06-2018 4-07-49 PM.JPG

Underside March Notice the long sap-feeding mouthpart lying along its undersid
Green Vegetable Bug - Nezara viridula .JPG 

First instar nymphs of Green vegetable bug, (Nezara viridula) by their empty eggshells, note the black T-shaped egg burster in the hatched eggs. Hatching occurs with the help of a T-shaped egg burster, which is ridging on an embryonic head used to mechanically rupture the eggshell’s operculum during eclosion. (Click image to enlarge)
Green vegetable bug -002.jpg

A second stage instar, 2mm body length.
Second instar nymph Nezara viridula 1 .JPG  

Mid-stage instar.
Mid instar Nezara viridula Green Vegetable bug.JPG

Mid-stage instar
Mid instar Nezara viridula Green Vegetable bug-002.JPG

Mid-stage instar underside
Mid instar Nezara viridula Green Vegetable bug-003.JPG

The next four photos are of final instars of Nezara viridula.(8 mm long)
Nezara viridula Southern Green Shieldbug-004.JPG

Southern Green Stink Bug Nezara viridula.JPG  

This the empty moulting shell of the above last instar.  
Moulting shell of last instar Nezara viridula.JPG

Immature Green vegetable bug Nezara viridula 1 .JPG

Green vegetable bug, Nezara viridula 665x907.jpg 
Thanks to New South Wales  Department of Trade and Investment, Regional Infrastructure and Services for this copyright image. 

Thanks to Wikipedia for text and information: