This common bug has a flattened, shield-shaped body, as the name suggests. It is bright green in colour with delicate flecks of black that look like small puncture marks. In November, the insects darken in colour and spend the winter hibernating with a dark-bronze colouration. Although the sexes are similar in appearance, females tend to be larger than males. Like all bugs (Hemiptera), the green shield bug has specialised sucking mouthparts, which in this species are used to feed on plant sap. This species belongs to a sub-order known as the ?true bugs? (Heteroptera) in which only the tips of the wings are membranous; the rest of the wing is hardened. When the bug is at rest, the wings are held flat over the body and the membranous parts of the wings overlap.