INTERESTING INSECTS

By N A Martin (2016, revised 2018)

Green vegetable bug, Southern green stink bug

Cimex viridulus Linnaeus, 1758

Cimex smaragdulus Fabricius, 1775

Cimex torquatus Fabricius, 1775

Nezara approximate Reiche & Fairmaire, 1848

Nezara aurantiaca Costa, 1884

The cosmopolitan Green vegetable bug was found in Northland, New Zealand in 1944. This adventive shield bug is now found throughout the North Island and in the warmer parts of the South Island. It feeds on native plants and is a pest of vegetable, arable, fruit and nut crops.

Conservation status: Widespread, living on some native plants and a major pest of some vegetable and agricultural crops

The insect overwinters as adults often at the base of clumps of plants such as Agapanthus. During winter and spring they may be seen siting in the sun. Adults appear to gather in suitable overwintering sites and on plants for breeding. They are probably attracted to each other by an aggregation pheromone (volatile chemical). The first eggs are laid in spring. These hatch into nymphs that develop into adults by early summer. There are two or more generations per year. In late summer females stop laying eggs.

The adults are 14-16 mm long; the males are slightly smaller than the females. The normal body, forewings and leg colour is green. Sometimes yellow/orange or brown adults may be seen. At the base/front of the scutellum is a line of three tiny white spots. On the underside the body is a long rostrum that holds the stylets used for feeding. Like most insects, there are three pairs of legs. Also like a typical shield bug adults have two pairs of wings. The partly green forewings cover and protect the hind wings.

After mating, the female lays several batches of eggs. Eggs are laid in a large raft of 40-80 on the underside of leaves or other sheltered locations. The eggs are like short cylinders with straight sides. The eggs are yellow when first laid, but turn pink before they hatch. The nymph uses a dark T-shaped structure called an egg burster to help push the top off the egg.

Nymphs hatch from the eggs. First instar nymphs are like small, red and black, wingless adults. There are five nymphal stages, each is called an instar. Nymphs go from one stage to the next by moulting, changing their skin. During moulting, the "skin" on the dorsal side splits and the next stage pulls itself out. As the insects progress through the nymphal stages their body changes colour. The first instar is almost circular in outline. The body is red with black around the abdominal scent gland openings, black areas also on the thorax and a black head, legs and antennae. The second instar is shiny black. The abdomen has a pair of white lateral patches on the first segment and two pairs of tiny orange spots near the scent glands. The third instar is also black, but has more white on the first abdominal segment and more small yellow or white spots on the abdomen. The lateral edges of the prothorax and mesothorax (first and second segments of the middle section of the body) are coloured. The colour of fourth instar nymphs is more variable. The background colour may be black or green and the lateral edge of each abdominal segment may have an area of pink. Antennae and legs vary from pink to dark brown. The small wing buds extend to the edge of the abdomen. Fifth instar nymphs are even more variable. They may be almost black to almost green with a pink abdominal fringe. Amongst the variable patterns, they all have three pairs of white or yellow abdominal spots near the scent glands. Most also have more small white spots. The wing buds extend onto the abdomen.

The rate of development depends on temperature. In summer eggs take about 20 days to hatch, while the nymphal stage lasts about 80 days. In Auckland there are about three generations per year.

Walking and flying

The nymphs and adults have three pairs of legs. The adults have two pairs of wings; the front pair is modified to protect the hind wings. Part of the forewing is coloured green, while the rest is membranous.

Feeding

Like other Hemiptera, the green vegetable bug has piercing and sucking mouth parts. Two pairs of long stylets, special shaped rods, are held in the rostrum. When it feeds the bug moves the tip of the rostrum to a berry or other suitable part of the plant. The stylets are then gradually pushed into the plant. The maxilla (inner pair of stylets) form two tubes, one through which saliva is injects into the plant and a second through which plants juices are sucked up into the insect.

Adult Green vegetable bug, Nezara viridula, (Hemiptera: Pentatomidae), note the three white spots. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2BG9]

Underside of an adult Green vegetable bug, Nezara viridula, (Hemiptera: Pentatomidae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2BFB]

Adult Green vegetable bug, Nezara viridula, (Hemiptera: Pentatomidae) showing the rostrum hanging down. Creator: Tim Holmes. © Plant & Food Research. [Image: 2BFA]

Two adult Green vegetable bug, Nezara viridula, (Hemiptera: Pentatomidae) showing variations in colour. Creator: DSIR Photographers. © Landcare Research. [Image: 2BGA]

An orange variant adult Green vegetable bug, Nezara viridula, (Hemiptera: Pentatomidae). Creator: DSIR Photographers. © Landcare Research. [Image: 2BGH]

A pair of mating Green vegetable bugs, Nezara viridula, (Hemiptera: Pentatomidae). Creator: Martin Heffer. © Plant & Food Research. [Image: 2BFC]

Eggs of Green vegetable bug, Nezara viridula, (Hemiptera: Pentatomidae) shortly before hatching. Creator: Tim Holmes. © Plant & Food Research. [Image: 2BFM]

First instar nymphs of Green vegetable bug, Nezara viridula, (Hemiptera: Pentatomidae) by their egg shells, note the black T-shaped egg burster in the hatched eggs. Creator: Tim Holmes. © Plant & Food Research. [Image: 2BFN]

Eggshells of Green vegetable bug, Nezara viridula, (Hemiptera: Pentatomidae), with moulted skins of 1st instar nymphs and a 2nd instar nymph. Creator: Tim Holmes. © Plant & Food Research. [Image: 2BFP]

Second instar nymph of Green vegetable bug, Nezara viridula, (Hemiptera: Pentatomidae), note the two pairs of tiny orange spots on the abdomen. Creator: Tim Holmes. © Plant & Food Research. [Image: 2BFQ]

Second instar nymphs of Green vegetable bug, Nezara viridula, (Hemiptera: Pentatomidae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2BFR]

Third instar nymphs of Green vegetable bug, Nezara viridula, (Hemiptera: Pentatomidae) on a berry of black nightshade, Solanum nigrum. Creator: Tim Holmes. © Plant & Food Research. [Image: 2BFS]

Underside of third instar nymph of Green vegetable bug, Nezara viridula, (Hemiptera: Pentatomidae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2BFV]

Fourth instar nymph of Green vegetable bug, Nezara viridula, (Hemiptera: Pentatomidae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2BFF]

Underside of fourth instar nymph of Green vegetable bug, Nezara viridula, (Hemiptera: Pentatomidae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2BFG]

Fourth instar nymph of Green vegetable bug, Nezara viridula, (Hemiptera: Pentatomidae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2BFJ]

Underside of fourth instar nymph of Green vegetable bug, Nezara viridula, (Hemiptera: Pentatomidae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2BFI]

Fifth instar nymph of Green vegetable bug, Nezara viridula, (Hemiptera: Pentatomidae), note the wing buds extending onto the abdomen. Creator: Tim Holmes. © Plant & Food Research. [Image: 2BFW]

Underside of fifth instar nymph of Green vegetable bug, Nezara viridula, (Hemiptera: Pentatomidae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2BFX]

Fifth instar nymph of Green vegetable bug, Nezara viridula, (Hemiptera: Pentatomidae), note the wing buds extending onto the abdomen. Creator: Tim Holmes. © Plant & Food Research. [Image: 2BFY]

Underside of fifth instar nymph of Green vegetable bug, Nezara viridula, (Hemiptera: Pentatomidae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2BFZ]

Fifth instar nymph of Green vegetable bug, Nezara viridula, (Hemiptera: Pentatomidae), note the wing buds extending onto the abdomen. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2BG8]

Third instar nymph of Green vegetable bug, Nezara viridula, (Hemiptera: Pentatomidae) feeding on Plantain, Plantago lanceolata, seed capsules; note the exposed stylets where the rostrum is bent. Creator: Nicholas A. Martin. © Nicholas A. Martin. [Image: 2BGB]

Several shield bugs look similar to the green vegetable bug. It is one of the two large green shield bugs in New Zealand. The smallest, green potato bug, Cuspicona simplex Walker, 1867, has distinctive sharp protruding corners of the pronotum (first segment of the thorax). The green vegetable bug and the Australasian green shield bug, Glaucias amyoti (Dallas 1851) are superficially similar. A helpful way of distinguishing between them is the presence of three small white spots in a line at the base of the scutellum in the green vegetable bug. Even the orange and brown variants of the green vegetable bug have the three white spots.

The egg masses of green vegetable bug are also distinctive and can be identified. The eggs are laid on the underside of leaves and other hidden places. There may be 40-80 eggs in a raft, with the eggs in neat tightly arranged rows. Each egg is finely sculptured and cylindrical with almost straight sides.

The Green vegetable bug nymphs are variable in colour, but all except the first instar nymphs have small yellow or white spots on the abdomen.

Side view of an adult Green vegetable bug, Nezara viridula, (Hemiptera: Pentatomidae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2BF9]

A pair of mating Green vegetable bugs, Nezara viridula, (Hemiptera: Pentatomidae). Creator: Martin Heffer. © Plant & Food Research. [Image: 2BFC]

Two adult Green vegetable bug, Nezara viridula, (Hemiptera: Pentatomidae) showing variations in colour. Creator: DSIR Photographers. © Landcare Research. [Image: 2BGA]

Eggs of Green vegetable bug, Nezara viridula, (Hemiptera: Pentatomidae) shortly before hatching. Creator: Tim Holmes. © Plant & Food Research. [Image: 2BFL]

Second instar nymph of Green vegetable bug, Nezara viridula, (Hemiptera: Pentatomidae), note the two pairs of tiny orange spots on the abdomen. Creator: Tim Holmes. © Plant & Food Research. [Image: 2BFQ]

Third instar nymphs of Green vegetable bug, Nezara viridula, (Hemiptera: Pentatomidae) on a berry of black nightshade, Solanum nigrum. Creator: Tim Holmes. © Plant & Food Research. [Image: 2BFT]

Fourth instar nymph of Green vegetable bug, Nezara viridula, (Hemiptera: Pentatomidae). Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2BG3]

Fourth instar nymph of Green vegetable bug, Nezara viridula, (Hemiptera: Pentatomidae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2BFK]

Fifth instar nymph of Green vegetable bug, Nezara viridula, (Hemiptera: Pentatomidae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2BFD]

Fifth instar nymph of Green vegetable bug, Nezara viridula, (Hemiptera: Pentatomidae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2BFH]

Fifth instar nymph of Green vegetable bug, Nezara viridula, (Hemiptera: Pentatomidae) on a berry of a poroporo, Solanum aviculare. Creator: Tim Holmes. © Plant & Food Research. [Image: 2BG1]

Fifth instar nymph of Green vegetable bug, Nezara viridula, (Hemiptera: Pentatomidae) on berry of a Solanum species. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2BG7]

No pathogens of green vegetable bug are known in New Zealand.

Predators

Green vegetable bugs have been recorded as being eaten by a bird, Starling, and by the German wasp. The scent glands may deter potential predators.

Parasitoids

In other countries there are many parasitoids, but in New Zealand only three parasitoids of green vegetable bugs are known. An egg parasitoid, Trissolcus basalis (Wollaston 1858), was released into New Zealand in 1949 to control green vegetable bug. The adult female lays an egg in an egg of the shield bug. The eggs turn black showing that they have been parasitised.

The other parasitoids were not deliberately released into New Zealand. One, Acroclisoides sp is also an egg parasitoid with a distinct black mark on its forewings.

The shield-bug nymphal parasitoid, Aridelus rufotestaceus Tobias, 1986, (Hymenoptera: Braconidae) kills nymphs and adult green vegetable bugs. It was discovered in New Zealand in 2010 by Stephen Thorpe. Aridelus rufotestaceus is known to parasitize nymphs of green vegetable bug. In laboratory experiments in Italy, nymphs of several sizes and adults were parasitised. The female wasps lay eggs in nymphs and may be adults. When the parasite larva is fully grown, it emerges from the nymph and spins a white cocoon in which it pupates. The adult wasp cuts open one end of the cocoon and climbs out. In 2016 it was also reared from Australasian green shield bug, Glaucias amyoti (Dallas 1851).

Eggs of the Green vegetable bug, Nezara viridula (Hemiptera: Pentatomidae) that are parasitized by a wasp, the Green vegetable bug egg parasitoid, Trissolcus basalis (Hymenoptera: Platygasteridae). Creator: Minna Personen. © Plant & Food Research. [Image: 2C6T]

Eggs of the Green vegetable bug, Nezara viridula (Hemiptera: Pentatomidae) that are parasitized by a wasp, the Green vegetable bug egg parasitoid, Trissolcus basalis (Hymenoptera: Platygasteridae). Creator: Minna Personen. © Plant & Food Research. [Image: 2C6U]

Eggs of the Green vegetable bug, Nezara viridula (Hemiptera: Pentatomidae) parasitized by the Green vegetable bug egg parasitoid, Trissolcus basalis (Hymenoptera: Platygasteridae); some wasps have emerged, while others are still emerging. Creator: Minna Personen. © Plant & Food Research. [Image: 2C6V]

Eggs of the Green vegetable bug, Nezara viridula (Hemiptera: Pentatomidae) parasitized by Green vegetable bug egg parasitoid, Trissolcus basalis (Hymenoptera: Platygasteridae); many wasps have emerged while others are still emerging. Creator: Minna Personen. © Plant & Food Research. [Image: 2C6Y]

Adult Green vegetable bug egg parasitoid, Trissolcus basalis (Hymenoptera: Platygasteridae) after emergence from eggs of the Green vegetable bug, Nezara viridula (Hemiptera: Pentatomidae). Creator: Minna Personen. © Plant & Food Research. [Image: 2C6X]

Underside of an adult Green vegetable bug egg parasitoid, Trissolcus basalis (Hymenoptera: Platygasteridae) after emergence from eggs of the Green vegetable bug, Nezara viridula (Hemiptera: Pentatomidae). Creator: Minna Personen. © Plant & Food Research. [Image: 2C6W]

Cocoon of shield-bug nymphal parasitoid Aridelus rufotestaceus (Braconidae) made by the larva after emergence from a nymph of Australasian green shield bug, Glaucias amyoti (Hemiptera: Pentatomidae). Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 293N]

Cocoon of shield-bug nymphal parasitoid Aridelus rufotestaceus (Braconidae) that had parasitised a nymph of Australasian green shield bug, Glaucias amyoti (Hemiptera: Pentatomidae). Note the opening in one end made by the adult wasp. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 293T]

Adult shield-bug nymphal parasitoid Aridelus rufotestaceus (Braconidae) that had parasitised a nymph of Australasian green shield bug, Glaucias amyoti (Hemiptera: Pentatomidae): top view of wasp. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 293Q]

Adult shield-bug nymphal parasitoid Aridelus rufotestaceus (Braconidae) that had parasitised a nymph of Australasian green shield bug, Glaucias amyoti (Hemiptera: Pentatomidae): underside of wasp. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 293P]

Adult shield-bug nymphal parasitoid Aridelus rufotestaceus (Hymenoptera: Braconidae) parasitizing a nymph of Green vegetable bug, Nezara viridula, (Hemiptera: Pentatomidae). © All rights reserved. [Image: 2I69]

Adult shield-bug nymphal parasitoid Aridelus rufotestaceus (Hymenoptera: Braconidae) parasitizing a nymph of Green vegetable bug, Nezara viridula, (Hemiptera: Pentatomidae). © All rights reserved. [Image: 2I6D]

Dead and live adult Acroclisoides sp. (Hymenoptera: Pteromalidae) after emerging from eggs of Schellenberg's soldier bug, Oechalia schellenbergii (Hempitera: Pentatomidae). Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2S4U]

Green vegetable bugs feed on fruit and stems of a wide variety of plants. Hosts include native species, weeds, garden flowers, vegetables, maize, fruit crops and macadamia nuts.

Feeding

Like other Hemiptera, the green vegetable bug has piercing and sucking mouth parts. Two pairs of long stylets, special shaped rods, are held in the rostrum. When it feeds the bug moves the tip of the rostrum to a berry or other suitable part of the plant. The stylets are then gradually pushed into the plant. The maxilla (inner pair of stylets) form two tubes, one through which saliva is injects into the plant and a second through which plants juices are sucked up into the insect.

Damage

Plants react in different ways to attack by the bug: beans shrivel and become deformed; the kernels of sweet corn and maize shrivel; and on tomatoes and tamarillos hard, corky growths appear where the fruit has been pierced.

Third instar nymph of Green vegetable bug, Nezara viridula, (Hemiptera: Pentatomidae) feeding on Plantain, Plantago lanceolata, seed capsules; note the stylets exposed where the rostrum is bent. Creator: Nicholas A. Martin. © Nicholas A. Martin. [Image: 2BGC]

Fourth instar nymph of Green vegetable bug, Nezara viridula, (Hemiptera: Pentatomidae) feeding on Haloragis erecta seed capsules; note the stylets exposed where the rostrum is bent. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2BG4]

Second instar nymph of Green vegetable bug, Nezara viridula, (Hemiptera: Pentatomidae) feeding on green carrot seeds. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2BG5]

Third instar nymphs of Green vegetable bug, Nezara viridula, (Hemiptera: Pentatomidae) on a berry of black nightshade, Solanum nigrum. Creator: Tim Holmes. © Plant & Food Research. [Image: 2BFT]

Corn cob with grey feeding damage caused by Green vegetable bug, Nezara viridula, (Hemiptera: Pentatomidae). Creator: DSIR Photographers. © Plant & Food Research. [Image: 2BGF]

Corn cob with black feeding damage caused by Green vegetable bug, Nezara viridula, (Hemiptera: Pentatomidae). Creator: DSIR Photographers. © Plant & Food Research. [Image: 2BGG]

Adult green vegetable bugs are very mobile and are attracted to suitable plants for feeding and breeding. The egg parasite helps keep populations of the green vegetable low and the new nymphal parasite should also help. However, they will still be attracted to suitable host plants.

In Home gardens, tomatoes, beans and sweet corn are favoured hosts. If there are only a few green vegetable bugs, the simplest solution is to pick them off and dispose of them. If there are a large number of adults and nymphs, you may have to use an insecticide. Consult your local garden centre of hardware store.

Growers of Commercial Crops, should consult their local association.

Why Stink bugs

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 bases 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.

Allan DJ. 1976. Green vegetable bug, Nezara viridula (Linnaeus, life cycle. New Zealand Department of Scientific and Industrial Research Information Series. 105 (17): 1-3.

Cameron PJ 1989. Nezara viridula (L.), green vegetable bug (Hemiptera: Pentatomidae). In: Cameron PJ, Hill RL, Bain J, Thomas WP ed. A. review of biological control of invertebrate pests and weeds in New Zealand 1874 to 1987. Technical Communication No. 10. Wallingford, England, UK, CAB International. Pp. 111-114.

Cumber RA 1964. The egg-parasite complex (Scelionidae: Hymenoptera) of shield bugs (Pentatomidae, Acanthosomidae: Heteroptera) in New Zealand. New Zealand Journal of Science 7 (4): 536-554.

Lariviere M-C, Larochelle A 2004. Heteroptera (Insecta: Hemiptera): catalogue. Fauna of New Zealand 50: 1-326.

Plant-SyNZ: Invertebrate herbivore-host plant association database. plant-synz.landcareresearch.co.nz/.

Shaw SR, Salerno G, Colazza S, Peri E. 2001. First record of Aridelus rufotestaceus Tobias (Hymenoptera: Braconidae: Euphorinae) parasitizing Nezara viridula nymphs (Heteroptera: Pentatomidae) with observations on its immature stages and development. Journal of Hymenoptera Research. 10: 131-137.

Graham Walker for information about control.

The New Zealand Plant & Food Research Institute Limited (Plant & Food Research) for permission to use photographs.

Landcare Research New Zealand Limited (Landcare Research) for permission to use photographs.

1 August 2018, NA Martin. Parasitoid list updated, photos of Acroclisoides sp added, Host plant table updated

1 February 2018. NA Martin. Updated captions of photos of egg parasitoids.

1 August 2017, NA Martin. Added new photos of Aridelus rufotestaceus ovipositing.