Green shield bug  (Palomena prasina)

Not threatened (2).

This common bug has a flattened, shield-shaped body, as the name suggests (3). It is bright green in colour with delicate flecks of black that look like small puncture marks (2). In November, the insects darken in colour and spend the winter hibernating with a dark-bronze colouration (2). Although the sexes are similar in appearance, females tend to be larger than males (2). Like all bugs (Hemiptera), the green shield bug has specialised sucking mouthparts, which in this species are used to feed on plant sap (4). 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 (2).

Widespread in England and Wales but becomes rare further north, especially in Scotland (1) (2). It is also found in mainland Europe where it is a minor pest (2).

Found in a wide range of habitats but becomes confined to woodlands in northern parts of its range (1). Its hosts include bushes and shrubs, but hazel is one of its preferred species (2).

Adult green shield bugs emerge from hibernation in May and mate in June (2). As with most bugs, individuals mate ‘back to back’ (4). The eggs are laid in hexagonal batches of around 28, and a single female will lay a number of batches so that the total number she lays will be around 100 (2). All bugs have a type of insect development known as ‘hemimetabolous development’ in which there is no larval stage but a number of wingless nymphs instead which resemble the adult form(4). This species passes through five nymphal stages, moulting between each one. Each stage has a different colouration, and the final stage has short wings. The adult stage is reached in September, and they go into hibernation in November (2).

This species is not threatened.

Conservation action is not required for this common species.

For more on bugs see the Natural History Museum’s It’s a Bug’s Life:
http://www.nhm.ac.uk/entomology/features/bugs/bugs.html

For more on invertebrates, their conservation and details of how to get involved see Buglife, the invertebrate conservation trust:
http://www.buglife.org.uk

• Larval: the stage in an animal’s lifecycle after it hatches from the egg. Larvae are typically very different in appearance to adults; they are able to feed and move around but usually are unable to reproduce.
• Nymphs: stage of insect development, similar in appearance to the adult but sexually immature.

1. National Biodiversity Network Species Dictionary (January2004): http://www.nhm.ac.uk/nbn
2. Southwood, T.R.E. & Leston, D. (1959) Land and water bugs of the British Isles The Wayside and Woodland Series. Frederick Warne & Co Ltd. London.
3. RSPB- Green shield bug (February 2004): http://www.rspb.org.uk/gardens/guide/atoz/g/greenshieldbug.asp
4. Martin. J. Hemiptera…It’s a Bug’s Life (February 2004): http://www.nhm.ac.uk/entomology/features/bugs/bugs.html