Shieldbugs are some of Ireland’s most familiar insects , getting their name from their shield-like body. They belong to the order Hemiptera or ‘True Bugs’, which also includes other familiar insects like Pond Skaters, Water Scorpions, Aphids and Flower Bugs.
Most shieldbugs are herbivorous, using their pointed mouthparts to feed on sap from a variety of plants but some may be carnivorous, feeding on soft-bodied moth or beetle larvae. They mostly hibernate as adults, hiding away in sheltered places to emerge and breed in the spring. The eggs are laid either individually or in clusters and the nymphs which subsequently emerge resemble the adults but are smaller, with no wings and a more rounded shape and are often seen in the summer months. They will spend 6-10 weeks in this stage before moulting and reaching the adult stage.
In Ireland there are 17 species of Shieldbug present, but only 6 of these have been recorded in my area. The commonest species in my garden is the Green Shield Bug, Palomena prasina which frequents hedgerows, shrubs and trees, feeding in particular on bramble. It is found throughout Ireland but is rare in the north and the central counties.
Another common species in the garden is the Gorse Shieldbug (Piezodorus lituratus) which is almost always found on gorse bushes. It is slightly smaller than the previous species with varying shades of green, blending in with gorse seed pods rather well. It is common in Ireland in areas of heath, scrub and gardens.
The third is the appropriately named Forest Shieldbug, Pentatoma rufipes. It is easy to identify being the only brown coloured shieldbug in the garden. It is fond of feeding on Oak and Alder trees but I suspect the ones that I have observed are feeding on Willow, Ash or Hazel. It is typically seen in the Autumn.
Two other similar-looking species that occur in the garden from time to time are the Hawthorn (Acanthosoma haemorrhoidale) and Birch (Elasmostethus interstinctus) Shieldbugs. As their names would suggest they feed primarily on Hawthorn and Birch respectively, but will also take Hazel, Oak and Aspen. Both species are predominantly green with brown markings, with the Birch Shieldbug being slightly smaller and brighter.
The final species, the Hairy Shieldbug (Dolycoris baccarum) is a recently established species, having spread northwards from the south of Ireland; my observations are possibly Ireland’s northernmost record! It is a peculiar member of this family being the only representative covered in hairs (hence its name). It is reportedly found in tall grassland, scrub and woodland edges and feeds mainly on Blackthorn.
I would suspect that the habitat in my local area would be suitable for a few other species, such as the Bronze and Parent Shieldbugs, but I am yet to see them. Maybe if I spend enough time clambering through thickets and scrub I’ll find a few to add to the list!
