Schellenberg's soldier bug - Oechalia schellenbergii
By N A Martin (2016, revised 2017)
Pentatoma schellenbergii Guérin, 1831
Arma schellembergi (Guérin, 1831)
Pentatoma consociale Boisduval, 1835
Oechalia consocialis (Boisduval, 1835)
Rhaphigaster perfectus Walker, 1867
Biostatus and Distribution
This native shield bug is present in New Zealand and Australia. Schellenberg's soldier bug is a predator that feeds on free living insects such as caterpillars and beetle larvae. It occurs in gardens and parks as well as in native ecosystems.
Conservation status: Schellenberg's soldier bug is a predator of insects in native ecosystems, in gardens and parks.
Life Stages and Annual Cycle
Schellenberg's soldier bug overwinters as adults that shelter in secluded places. There appears to be a single generation per year with eggs being found from December to March. Each female lays several batches of eggs. The nymphs grow into adults during summer and autumn.
The adults are 8-12 mm long; the males are slightly smaller than the females. The body and forewings have a pale background covered with dark punctures. The most striking feature are the pointed ‘shoulders’. The tip the scutellum is narrow and pale. The antennae are dark brown and the legs are pale brown. On the underside there is a long rostrum that holds the stylets used for feeding. Also on the underside is a forward pointing spine extending between the last two pairs of legs.
Several clusters of eggs are laid. The clusters are often made up of 14 or 28 eggs, one or two for each ovariole. The black eggs are usually arranged in rows. Each egg has a prominent ring of white spines on top.
The nymphs that hatch from the eggs are like small, wingless adults. There are five nymphal instars (stages). Nymphs go from one stage to the next by moulting, where the “skin” on the dorsal side splits and the next stage pulls itself out. The first instar nymphs are black and red; the black on the head, thorax and around the scent glands. The fifth instar is mainly coloured black with red on the abdomen around a central area of black. This stage has black wing buds that extend on to the abdomen.
The length of the lifecycle (time from egg to adult) varies with temperature and is faster at higher temperatures. In South Australian laboratory experiments, eggs developed from 15 to 30°C, taking 20 days at 15°C and 8 days at 20°C. At 20°C the five instars took 2.3, 4.6, 4.8, 7.6 and 11 days to complete development respectively.
Walking and flying
The nymphs and adults have six legs (three pairs) that are used for walking. The adults have two pairs of wings. The front pair is modified as covers for the hind wings. Part of the forewing is coloured brown, while the rest is membranous.
Like other Hemiptera, Schellenberg's soldier bug has sucking mouth parts. The long stylets, special shaped rods, are held in the rostrum. Schellenberg's soldier bugs are predators. The feed on free living insects such as caterpillars which they stab with their stylets, mandibles and maxillae. During feeding the insect is held by at the end of the rostrum the mandibles. The maxillae are inserted further into the prey. They form two tubes, a narrow duct down which saliva is pumped into the prey, and a larger tube up which the partly digested food is sucked.
The first instar nymph is the only stage that is not a predator. After hatching they stay by their eggs. They will probably drink water and may feed on plant juices.
There are several species of Pentatomidae in New Zealand that have dark coloured adults. Schellenberg's soldier bug adults have a distinctive triangular shape with obvious lateral points on the pronotum, the first segment of the thorax. The underside of an adult also has a pale forward pointing spine between the last two pairs of legs.
The black eggs have distinctive relatively long white spines on top. The last stage nymph is mostly black with bright red on the abdomen around a black middle area.
No predators or pathogens are known.
Eggs of the Brown soldier bug may be parasitized by two species of tiny wasps belonging to the family Platygasteridae. Trissolcus oenone (Dodd, 1913), a native species, parasitizes several native shield bugs. Another egg parasitoid, Trissolcus basalisi (Wollaston 1858), was released into New Zealand in 1949 to control the green vegetable bug, Nezara viridula. It also parasitizes eggs of other shield bugs including the Brown soldier bug. When this wide host range was discovered in the 1960s, it was regarded as beneficial, because at that time protection of crops was regarded as more important than protecting native insects. Eggs of other pentatomid species parasitized by T. basalis turn black.
|Scientific Name||Common Name||Classification||Enemy Type||Reliability Index||Biostatus|
|Trissolcus basalis (Wollaston, 1858)||Green vegetable bug egg parasitoid (Wasp)||Hymenoptera: Platygasteridae||parasitoid||10||adventive|
|Trissolcus oenone (Dodd, 1913)||Native shield-bug egg parasitoid (Wasp)||Hymenoptera: Platygasteridae||parasitoid||10||native|
The Schellenberg's soldier bug feeds on a variety of free living prey notably caterpillars and beetle larvae.
Like other Hemiptera, the Schellenberg's soldier bug has sucking mouth parts. The long stylets, special shaped rods, are held in the rostrum. They stab their prey with their stylets, mandibles and maxillae. During feeding the insect is held by at the end of the rostrum the mandibles. The maxillae are inserted further into the prey. They form two tubes, a narrow duct down which saliva is pumped into the prey, and a larger tube up which the partly digested food is sucked. The first instar nymph is the only stage that is not a predator.
|Scientific Name||Common Name||Classification||Reliability Index||Biostatus|
|Danaus plexippus (Linnaeus, 1758)||Monarch||Lepidoptera: Nymphalidae||10||adventive|
|Gonipterus scutellatus Gyllenhal, 1833||Gum-tree weevil||Coleoptera: Curculionidae||9||adventive|
|Helicoverpa armigera (Walker, 1857)||Tomato fruitworm||Lepidoptera: Noctuidae||10||adventive|
|Mythimna separata (Walker, 1865)||Northern armyworm||Lepidoptera: Noctuidae||9||adventive|
|Paropsis charybdis Stal, 1860||Eucalyptus tortoise beetle||Coleoptera: Chrysomelidae||10||adventive|
|Pieris rapae (Linnaeus, 1758)||white butterfly||Lepidoptera: Pieridae||10||adventive|
|Pseudocoremia suavis Butler, 1879||Common forest looper||Lepidoptera: Geometridae||10||endemic|
|Uresiphita maorialis (Felder & Rogenhofer, 1875)||Kowhai moth||Lepidoptera: Crambidae||10||endemic|
Why Stink bugs
Pentatomidae are often called stink bugs because when handled they emit a strong smell. The nymphs have prominent glands on the upper (dorsal) side of their abdomen, while adults have glands between the bases of their legs. The chemicals may deter predators and cause other bugs to drop to the ground, but some of the chemicals produced may also act as aggregation pheromones.
Do first instar nymphs imbibe surface liquid on plants and/or suck plant juices?
Awan MS. 1988. Development and mating behaviour of Oechalia schellenbergii (Guerin Meneville) and Cermatulus nasalis (Westwood) (Hemiptera, Pentatomidae). Journal of the Australian Entomological Society 27: 183-187.
Cumber RA. 1964. The egg-parasite complex (Scelionidae: Hymenoptera) of shield bugs (Pentatomidae, Acanthosomidae) in New Zealand. New Zealand Journal of Science. 7: 536-554.
Edwards PB, Suckling DM. 1980. Cermatulus nasalis and Oechalia schellenbergii (Hemiptera: Pentatomidae) as predators of Eucalyptus tortoise beetle larvae, Paropsis Charybdis (Coleoptera: Chrysomelidae) in New Zealand. New Zealand Entomologist. 7(2): 158-164.
Lariviere M-C. 1995. Cydnidae, Acanthosomatidae, and Pentatomidae (Insecta: Heteroptera): systematics, geographical distribution, and bioecology. Fauna of New Zealand. 35: 1-107.
The New Zealand Institute for Plant & Food Research Limited (Plant & Food Research) for permission to use photographs.
12 December 2016. NA Martin. Natural Enemy Table: biodiversity information corrected.