Green common Shieldbug (Palomena prasina)
What are shield bugs?
There are more than 40 species of shield bug in Britain, several species are common in gardens and are part of the biodiversity they support. The name shield bug is due to the shield-like shape of the adult insects when seen from above. All true bugs have sucking moth parts and most shield bugs feed on plant sap, although a few are predatory, most do not damage plants and can be encouraged in gardens. An identification guide can be found at British Bugs
The green shield bugs feed on sap and can be found on a wide range of plants. The adults, when viewed from above, have a distinctive shield-like shape.
Symptoms
The two main species of shield bug found in Britain can be difficult to distinguish.
Green shield bug
When fully grown the common green shield bug (Palomena prasina) is a broad, flattened, green insect with a strongly contrasting blackish brown darker area at the rear end, where the hind wings cross
The adult insects are about 10 mm (about 3/8in) long and are often seen basking in the sun in late summer on a wide variety of plants
This insect is native to Britain and is of widespread occurrence, especially in southern England
Nymphs of the native green shield bug have a rounded shape and are pale green, with some black markings during the earlier instars
It overwinters as adults, which usually turn brown. These are sometimes found in buildings
Southern green shield bug
In 2018 this species was numerous in south-east England and was the sixth most frequent enquiry to the RHS entomologists
Similar to the green shield bug, this species also overwinters as adults, which typically turn brown. These are sometimes found in buildings
Whilst this bug can be a problem in other parts of the world, the evidence so far in mainland Britain is that the southern green shield bug does not become numerous until late summer or early autumn, by which time beans are coming to the end of their cropping period and so little damage is caused
This species can cause damage to some vegetables, especially runner and French bean pods, but it remains to be seen whether it will become established to the extent that it becomes a problem in Britain
The nymphs of southern green shield bugs are green or black with many white, yellow or pinkish-red circular markings on their upper surface
The adults are uniformly green and lack a dark area at the rear end of the body
This arrival from mainland Europe is up to 12 mm (about ½ in) long, making it slightly larger than the green shield bug
In 2003 the southern green shield bug (Nezara viridula) was found breeding for the first time in the London area
Southern Green Shieldbug (Nezara viridula)
Other Shield Bugs include:
Family: Acanthosomatidae Key features: Tarsi 2-segmented
Family: Scutelleridae Key features: Scutellum extends to end of abdomen, tarsi 3-segmented
Family: Cydnidae Key features: Tibiae with strong spines, tarsi 3-segmented
Legnotus limbosus Bordered Shieldbug
Legnotus picipes Heath Shieldbug
Geotomus punctulatus Cornish Shieldbug
Geotomus petiti
Tritomegas bicolor Pied Shieldbug
Tritomegas sexmaculatus Rambur's Pied Shieldbug
Canthophorus impressus Down Shieldbug
Adomerus biguttatus Cow-wheat Shieldbug
Sehirus luctuosus Forget-me-not Shieldbug
Family: Thyreocoridae Key features: Scutellum covering most of abdomen, small & dark species
Family: Plataspidae Key features: Scutellum covering entire abdomen, small & dark species
Family: Pentatomidae Key features: Tarsi 3-segmented
Graphosoma italicum Striped Shieldbug
Podops inuncta Turtle Shieldbug
Dyroderes umbraculatus White-shouldered Shieldbug
Sciocoris cursitans Sand-runner Shieldbug
Sciocoris homalonotus
Sciocoris sideritidis
Aelia acuminata Bishop's Mitre Shieldbug
Neottiglossa pusilla Small Grass Shieldbug
Eysarcoris venustissimus Woundwort Shieldbug
Eysarcoris aeneus New Forest Shieldbug
Peribalus strictus Vernal ShieldBug
Dolycoris baccarumHairy ShieldBug
Piezodorus lituratus Gorse Shieldbug
Pentatoma rufipes Red-legged Shieldbug
Carpocoris purpureipennis
Rhaphigaster nebulosa Mottled Shieldbug
Halyomorpha halys Brown Marmorated Shieldbug
Eurydema oleracea Brassica Shieldbug
Eurydema dominulus Scarlet Shieldbug
Eurydema ornata Ornate Shieldbug
Picromerus bidens Spiked Shieldbug
Troilus luridus Bronze Shieldbug
Rhacognathus punctatus Heather Shieldbug
Zicrona caerulea Blue Shieldbug
Mecidea lindbergi
Control
The native common green shield bug is harmless, it is part of the biodiversity a healthy garden can support and control measures are not required
The southern green shield bug has not yet become numerous enough to cause damage to crop plants. Large numbers have only been seen from August onwards when crop damage is likely to be insignificant and therefore control is unlikely to be necessary
Biology
Sometimes mistaken for beetles, shield bugs belong to a different group of insects, the Hemiptera or true bugs, these all have sucking mouthparts
Green shield feed by sucking sap from a wide range of plants, but the native green shield bug causes no noticeable damage to cultivated plants, even when numerous
Both types of green shield bug overwinter as adults but before seeking sheltered places, they are often seen in late summer and autumn sitting on plant foliage in the sun. They often turn brown when overwintering
They are also active in early summer, when they lay small clusters of eggs on the undersides of leaves
The nymphs have a rounded body shape and gradually take on the adult appearance as they develop
In recent years, the green shield bug has become more abundant and widespread in Britain
The introduced southern green shield bug has become established, and is likely to become more widespread, at least in southern England
There are about 30 other species of shield bugs, which are brown or yellowish green with reddish markings. Some of these can also be found in gardens, none of these will damage garden plants
Some more information on British shield bugs can be found at the British Bugs website
