Southern Green Shieldbug

• Newly hatched nymphs do not feed and stay clustered beside the empty eggs: the cluster protects them from drying out and pools their chemical defences against predators.
• It passes through five nymphal stages and changes colour completely at each one, from orange to black with white and yellow markings and finally to green.
• It is the only representative of the genus Nezara on the Iberian Peninsula.
• It communicates by vibration. Males and females locate each other by vibrating the abdomen and transmitting those signals through the stem of the plant, not through the air. Each species has its own vibratory repertoire, and that channel is the basis of their sexual recognition.
• That communication is being turned against it: traps are being trialled that emit synthetic vibrations through the stem to interfere with mating — a vibratory version of pheromone mating disruption.
• Its defence is chemical: when disturbed it releases, from glands in its thorax, a mixture of aldehydes with an intense, persistent smell — the origin of popular names like stink bug.
• It pierces fruits and seeds with its stylet and injects enzymes, leaving blemishes and deformities that make the harvest unsaleable even though the damage is superficial.
• It probably originated in Ethiopia and has spread through all the warm regions of the world with the agricultural trade.
• Its range is expanding towards northern Europe with the warming climate.

Skeleton type

Invertebrate - chitin exoskeleton (insect)

Habitat and environment

A cosmopolitan and highly polyphagous species: vegetable plots, arable crops, fruit trees, vineyards, glasshouses and spontaneous vegetation along field margins. It overwinters as an adult among leaf litter, in shrubs or even in the structure of glasshouses

Size at birth

Eggs roughly 1 mm tall, barrel-shaped with flattened ends and a conspicuous belt of spines

Sexual maturity

The full cycle, from egg to adult, takes between 35 and 70 days depending on temperature

Gestation / incubation

The eggs hatch between 5 and 21 days after laying, depending on temperature

Litter / clutch size

Clutches of 30 to 130 eggs arranged like a honeycomb on the underside of leaves; a female can lay between 200 and 300 eggs over her lifetime

Sources consulted: SERIDA - Servicio Regional de Investigación y Desarrollo Agroalimentario del Principado de Asturias; IVIA - GIP Cítricos; Cajamar (ficha técnica 010, 2015); IFAPA - Junta de Andalucía; Catalán y Verdú 2005, Bol. San. Veg. Plagas 31; Ferrari, Schwertner y Grazia 2010, Zootaxa 2424

Best time: From spring to well into autumn, with population peaks in late summer