Species: Parent Bug (Elasmucha grisea)

Family: Shield bug (ACANTHOSOMATIDAE)

Category: Insects (Other)

Location: One Sighting

A. Insects (Other)

More extensive information on insects can be found in a separate blog post.

B. Shield bug (ACANTHOSOMATIDAE)

The Acanthosomatidae is a family of shieldbugs that consists of perhaps 200 species. Each species has its own preferred habitat, usually a specific tree or family of trees.

C. Parent Bug (Elasmucha grisea)

These shieldbugs live on or near Silver Birch or Alder trees. Males are typically smaller than females, at between 7 and 9 millimetres. The markings on the scutellum of these insects easily identifies them, even in their nymph form. They overwinter as adults and emerge during the spring. New adults are found from August onwards.

This insect's name has been applied in recognition of behaviour that is relatively rare for insects: females of the species engage in prolonged caring for eggs and juveniles. Without this care, broods can easily be taken by ants, beetles and earwigs. When faced with such threats to their young, these insects may jerk their bodies, fan their wings, or face towards the threat with a menacing posture (effectively calling the predator's bluff). If all these fail, they are capable of discharging a foul odour from their scent glands. Shieldbugs with this ultimate capability are often called 'stink bugs' for good reason. The French call them punaise and sometimes punaise nez-de-rat. (Language hints: poo-what-a-stink, nez = nose, rat = guess what?)

Images

Parent Bug

This insect's name has been applied in recognition of behaviour that is relatively rare for insects: females of the species engage in prolonged caring for eggs and juveniles. Without this care, broods can easily be taken by ants, beetles and earwigs. When faced with such threats to their young, these insects may jerk their bodies, fan their wings, or face towards the threat with a menacing posture (effectively calling the predator's bluff). If all these fail, they are capable of discharging a foul odour from their scent glands.

(Photo credit: Stuart MA Ball.)

Parent Bug

These insects are between 7 and 9 millimetres in length. The female shown in this photograph is clearly protecting her large clutch.

Look closely, and you will see two cream-coloured marks either side of the insect's head. These are larvae of a parasitic fly. This will be either Ectophasia crassipennis or Subclytia rotundiventris. Both are tachinid flies (we've seen three species of this family, but neither of the ones mentioned here - not yet) which insert eggs one at a time into the bug's upper thorax. After the egg hatches, it feeds on its host, initially taking only non-vital parts. Eventually, the bug will be consumed from the inside and the fly larvae will pupate outside the host. Until this final stage, the parasite allows the bug to continue caring for its clutch.

(Photo credit: Stuart MA Ball.)

Parent Bug

This group of Parent Bug nymphs was photographed in August on a Silver Birch tree, one of their preferred hosts.

(Photo credit: Stuart MA Ball.)

Parent Bug

Parent bug nymphs photographed in August 2023.

(Photo credit: Stuart MA Ball.)

Parent Bug

Parent bug nymphs photographed in August 2023.

(Photo credit: Stuart MA Ball.)