Щитовка серая (Elasmucha grisea)

Species of true bug
Speciesbox
| name = Parent bug
| image = Acanthosomatide Elasmucha grisea 001. JPG
| image caption = Elasmucha grisea, upperside
| image2 = 2013 06 04 15 34 47 Hemiptera. JPG
| image2 caption = Front view
| taxon = Elasmucha grisea
| authority = (Linnaeus, 1758)
| synonyms =
Cimex grisea Linnaeus, 1758

Elasmucha grisea is a rather common and widespread species present in most of Europe.

Elasmucha grisea can reach a length of Males are smaller than females. These medium sized shield bugs are usually brown reddish, but there are also gray (hence the Latin species name grisea) and green brown specimens. The connexiva are black and white. The upper side is covered with several dark dots. The scutellum usually shows an evident black patch. The ventral face is largely punctuated with black. The lateral corners of the pronotum are simply beveled. The front corners of the pronotum show a more pronounced tooth. Antennae are blackish in the male, dark brown in the female. This species, like other parent bugs, possesses methatoracic and abdominal glands, which discharge a foul smelling secretion. This secretion is used to deter potential enemies and is sometimes released when the bug is disturbed.

Adults of E. grisea can be found all year around. In fact this species overwinters as an adult. Mating occurs in the spring and new adults can be found in August. They obtain symbionts at an early age: the mother covers her eggs with bacteria so that the nymphs ingest them as they feed on the egg case. However, they seem to avoid trees with a high predation risk.

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. Predators, such as bugs, beetles, earwigs and ants, can eliminate all the offspring of the parent bug if there is no maternal care. 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,

After oviposition, the parent bug female stands over the egg batch and shields it throughout egg development. Predation appears to limit the clutch size in E. grisea. Experiments have shown that large females lay larger egg clutches than small females. However, when the clutch size was manipulated, small females protecting large clutches lost significantly more eggs than large females guarding small clutches or females in the control groups (guarding clutches of optimal size). After hatching, larvae of the parent bug remain in a tight aggregation, feeding on their empty egg shells. The tachinid fly, Subclytia rotundiventris, is a specialist endoparasite of the parent bug females. 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. The larva ‘permits’ the parent bug to continue caring for the juveniles until their third stage. 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. Considering that the older nymphs are more mobile and may escape from predators, some offspring of the parasited females of the parent bug probably survive and may also be potential hosts for the new generation of the parasite.