Common Gum Tree Shield Bug: Poecilometis patruelis

Adult Common Gum Tree Shield Bug
the red colour is because it has just moulted. The body darkens gradually.

Location: Bunbury

Season: Summer, December/January

Order: Hemiptera 

Suborder: Heteroptera 

Infraorder: Pentatomomorpha 

Superfamily: Pentatomoidea

Family: Pentatomidae

Tribe: Halyini

Poecilometis patruelis 

(Eumecopus patruelis)

All the stages of this Shield Bug were taken from my garden (which has a backdrop of bush with lots of gum trees). Identification of this Shield bug has been quite an interesting process. There are many genera and species of Shield Bugs that live on Gum Trees in Australia and they share many morphological similarities. Brisbane Insects has been a great resource for identification which mentions Mullerian Mimicry Complex. They mimic each others' features in order to ward off a common predator. Similar Shield Bugs are Gum Tree Shield Bug (Theseus modestus), Two-dots Shield Bug (Poecilometis monteithi), Brown Shield Bug (Poecilometis Sp.). They are identified based on wing venations, segments of antennae and placement of mouth parts. Common Gum Tree Shield Bug is the commonest in the region, hence the identification.

Egg shells 

2nd or 3rd Instar Nymph

3rd or 4th Instar Nymph

Adult Common Gum Tree Shield Bug

General Features of Family Pentatomidae:

1. Pentatomidae: Greek for 5 sections referring to the body shape which has 5 parts (Pronatum, Scutellum, 2 pairs of wings and membranous area at the tip). They have a hardened scutellum, resembling a shield, hence the name Shield Bug.

2. They have glands that release foul smelling substances to avert predators.

3. Segemented Antennae (4 to 5 segements).

4. Piercing mouth parts, even in the nymphs.

5. Wings: They belong to suborder Heteroptera (Greek for different wings)

The fore wings are known as hemelytra. The base of each wing is hardened. The tips of the fore wing and hind wings are thin. 

6. The eggs hatch into Nymphs which moult to lose the exoskeleton in 5 different stages. They are referred to as Instars. The nymphs have sucking mouth parts. They don't have wings, hence flightless.