Southern green shield bug
Nezara viridula
Role in the garden
A large piercing bug of vegetable and fruit crops. On tomatoes, its punctures leave tiny spots on young fruit, then white to yellow patches over white, spongy flesh on ripe fruit; it also damages bean pods. Probably native to Ethiopia, it has spread through tropical and subtropical regions; in France, it is often found in the wild and under cover.
Activity period
April to October; the adult, green in summer, turns brown in autumn and overwinters under cover (greenhouse and tunnel structures, buildings)
How to attract / manage it
Nets and clearing crop debris (INRAE).
Practical guide
Where to find them
On tomatoes, peppers, aubergines and cucumbers, often under cover, and on bean pods; off-white, barrel-shaped eggs packed together under the leaves; dark or green nymphs with pale spots, which spread over the plant.
Prevention
Put insect nets over the openings of greenhouses and tunnels and clear away plant debris and crop residues (INRAE); look under the leaves for egg clusters.
Early signs
Tiny dot-like spots on young tomatoes, paler underneath when cut; on ripe fruit, white to yellow patches and spongy flesh; wilting leaves at the shoot tips; distorted bean pods; a strong smell when the bug is disturbed.
Action / control
In the vegetable garden, damage often stays low: in the United Kingdom, the RHS notes that the bug only becomes numerous in late summer, when beans are finishing their cropping. Under cover, nets over the openings and clearing of debris (INRAE).
Sources
- INRAE, Ephytia : « Tomate, Punaises » (Nezara viridula) ; Biocontrol, « Nezara viridula (Punaise verte ponctuée) » ; Agiir, « Nezara viridula »
- RHS (Royal Horticultural Society) : Green shieldbugs (rhs.org.uk/biodiversity/green-shield-bugs)
Favourite plants / resources
Related plant entries
Tomato
Central plant of the tomato guild. The neighbouring basil is reputed to hinder aphids through its volatile compounds.
Cucumber
A trailing cucurbit cross-pollinated by bees and bumblebees. Sow in pots in April or in place after mid-May; staking is essential beyond 1 m. Prone to leaf spot and downy mildew in late summer, water at the base only, mulch abundantly, space plants 60-80 cm apart.
Bean
A nitrogen-fixing legume: in symbiosis with Rhizobium bacteria housed in its root nodules, it fixes nitrogen from the air, first for itself; part of it returns to the soil as its roots and haulm decompose, mainly benefiting the following crops. It belongs to the Three Sisters: maize serves as its stake and squash blankets the ground at its feet. Climbing varieties occupy the vertical layer while dwarf ones fill the low storey, two ways of inhabiting the bed. Its flowers feed bees and bumblebees, and at season's end, cutting the plants at the collar and leaving roots and haulm in place returns part of the nitrogen to the soil; the nitrogen in the seeds leaves with the harvest. Grown ahead of hungry vegetables, it readily opens a rotation.
Sweet pepper
A fruiting nightshade, hungry for both warmth and fertility: it calls for rich soil and a well-exposed bed among the summer crops. Basil, a classic companion to both tomato and pepper, is reputed to keep certain pests away through its aromatic compounds, while the French marigold, in a dedicated, dense planting, reduces soil nematodes (see its own entry) and draws in beneficial insects. Its flowers are visited by bees and by hoverflies, whose larvae devour aphids. Like any nightshade, it belongs in a rotation that avoids following tomato or potato, so as not to concentrate the family's shared soil diseases (verticillium wilt, for instance). Finally, it is kept away from fennel, reputed to hinder its neighbours.