Nature Table: Shield Bugs

Seventeen species of shield bug have been recorded in Ireland but some have a very localised distribution and others haven’t been seen for many decades.

The commoner ones are large insects with a flattened body shaped like a knight’s shield. They come in a variety of colours and this can vary according to the time of year. They spend most of their time in foliage and the species of plant they inhabit is a useful, though not infallible, guide to identifying the exact species. Ireland’s commonest species, the hawthorn shield bug, is normally found in hawthorn but can occur in oak, birch and hazel. Most Irish shield bugs feed on plant juices which they suck out using a hollow, pointed mouth called a rostrum.

A few are predators and stick their rostrum into things like caterpillars and beetle larvae. The parent shield bug, which feeds on birch and alder sap, is unusual among insects because the female protects them from predators and parasites.