These medium-sized shield bugs are usually brown-reddish, but there are also gray (hence the Latin species name grisea) and green-brown specimens.

[5] This species, like other parent bugs, possesses metathoracic and abdominal glands, which discharge a foul smelling secretion.

[8] Both adults and nymphs readily feed on developing seeds, and breeding individuals can be observed on host plants with many young catkins.

The common name of "parent bug" comes from the relatively rare insect behaviour of prolonged caring for eggs and juveniles, exhibited by females of this species.

The repertoire of female defensive behaviours includes wing fanning, body jerking, tilting towards the enemy and, finally, releasing of 'nasty' odours from the scent glands,[9][10][11] After oviposition, the parent bug female stands over the egg batch and shields it throughout egg development.

[12] After hatching, larvae of the parent bug remain in a tight aggregation, feeding on their empty egg shells.

Finally, larvae form smaller groups and disperse at the end of the third instar, at which point the female leaves them.

[14] The parasite inserts a single egg through the upper prothorax of an E. grisea female and, after hatching, the larva feeds on its host.

At the beginning the parasite feeds only on the non-vital parts of the bug, but finally it kills it and pupates outside the host.

In experiments, the wing-fanning (regarded as the most effective defensive behaviour of the parent bug) did not differ significantly between parasited and non-parasited females until the nymphs were at the second instar stage.

However, with older nymphs, females were much less effective in their defensive behaviour and often died before the end of maternal care.