Nezara viridula

What is a Green Vegetable Bug?

The green vegetable bug (AKA shield bug, or stink bug) is bright green in colour and about 1.5 cm long as an adult. It's mostly active in warm weather, during summer and autumn (but it does overwinter, so adults can be spotted throughout the year). 

Juvenile nymphs start out more rounded in shape, and change colour as they moult, from orange to black and white, or black and red. Nymphs go through 5 different stages of development (or instars), with each instar having a distinctive colour and pattern.

The green vegetable bug has piercing 'stylet' mouthparts that allow it to inject saliva into plants and suck out plant juices. It feeds on the sap extracted from stems and leaves, along with the juices from fruit or berries.

If disturbed (or squashed), this pest emits an unpleasant defensive chemical with an intensely foul odour, which can stain fingers and clothes, so be sure to wear gloves if you are manually removing bugs. Manual squashing is quite effective, as the odour from a dead bug seems to encourage the others to leap out of the host plant, making it easier to see (and squash) them. The odour also appears to discourage new bugs from entering the area.

To help reduce the bug population, check for yellow or pinky-coloured egg clusters stuck to the underside of leaves - remove the leaves and squash the egg masses underfoot, as soon as you see them.

Green vegetable bug nymph

Symptoms

Wilting plant shoots, from sap loss. Fruit can become distorted and misshapen, especially beans. Hard corky growths can appear around where bugs have pierced the plant to feed.

Plants impacted

  • Beans
  • Tomatoes
  • Capsicums
  • Potatoes
  • Beets
  • Sweet Corn
  • Grapes
  • Passionfruit
  • Avocado
  • Tamarillos
  • Citrus
  • Sunflowers
  • Other ornamentals (Aquilegia, Lavender)
  • Native plants (Kōwhai , Kakabeak, Karamū, Mingimingi)
  • Weeds (Dock, Nightshade, Ragwort, Thistles, Privet)

Green vegetable bug nymphs


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