Cermatulus nasalis hudsoni Woodward, 1953
Alpine brown soldier bug
Three subspecies are recognised in New Zealand:
C. nasalis hudsoni Woodward 1953 is present in alpine areas of the South Island of New Zealand,
C. nasalis nasalis (Westwood, 1837) is present in Australia, Timor and New Zealand,
C. nasalis turbotti Woodward 1950 is found only on the Three Kings Islands, New Zealand.
Biostatus and distribution
This species of native shield bug is present in New Zealand, Australia and Timor. The endemic subspecies, Alpine brown soldier bug, Cermatulus nasalis hudsoni is one of three subspecies in New Zealand. It is only found in alpine areas of the South Island.
Conservation status: This subspecies is only found in alpine areas in the South Island.
Life stages and annual cycle
Not much is known about the biology of the Alpine brown soldier bug. The annual cycle is probably similar to that of the Brown soldier bug, Cermatulus nasalis nasalis, that overwinters as adults that shelter in secluded places. There probably a single generation per year with eggs being found from November to February. Each female can lay several batches of eggs. The nymphs grow into adults during summer.
The adult females are about 10 mm long. Males are probably slightly smaller. The body, forewings and three pairs of legs are dark brown. The dorsal (upper) surface is covered with fine punctations that are surrounded by a ring of dark brown or black. There are three pale marks at the base of the scutellum. Part of the lateral edge of the head, thorax, forewings and abdomen are white. The antennae are red and black. On the underside there is a long rostrum that holds the stylets used for feeding.
Eggs are laid in clusters that may be small, about to 14 eggs, one for each ovariole or larger. The black eggs have a ring of short white spines on top and are arranged in several rows on leaves or bark.
The nymphs that hatch from the eggs are like small, black, wingless adults. When they push their way out of the egg with the aid of the T-shaped egg burster, the nymphs are red, but they soon develop the black pigment. 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 on top with an orange-red patch on either side of their abdomen. The abdomen is dark red, almost black. The terminal portion of some antennal segment is pale red. The second instar is similar.
Third instar nymphs have a blacker abdomen with two orange red patches at the front and another two at the rear. The underside of the abdomen is red with orange-yellow markings near the lateral margin of each segment. The fourth instar is similar, but has small wing buds and pale red lateral markings on the prothorax. The fifth instar is similar, but has larger wing buds. The basal two thirds of the second antennal segment is red. The underside of the abdomen brown with black areas centrally and laterally on each segment. The segments also each have a small lateral paler area.
The length of the lifecycle (time from egg to adult) varies with temperature and is faster at higher temperatures.
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, the Alpine brown soldier bug has sucking mouth parts. The long stylets, special shaped rods, are held in the rostrum. The Brown soldier bugs are predators. They feed on free living insects such as caterpillars which they stab with their stylets, mandibles and maxillae. During feeding the insect is held at the end of the rostrum by 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 drink water and it is reported that they might feed on plant juices.
There are several species of Pentatomidae in New Zealand that have brown adults. The nymphs of which are also distinctive.
The Alpine brown soldier bug, Cermatulus nasalis hudsoni, is covered with fine punctations surrounded by a ring of dark brown. There are three pale marks at the base of the scutellum. Part of the lateral edge of the head, thorax, forewings and abdomen are white. The antennae are red and black.
The Brown soldier bug, Cermatulus nasalis nasalis, is coloured shades of orange-brown to dark brown with black markings and is covered with fine punctations that are usually surrounded by a ring of pale to dark brown or black. The rounded end of the scutellum is usually pale yellow-brown. There is usually a darker patch on the forewing. The antennae are brown.
Schellenberg's soldier bug, Oechalia schellenbergii, another predator, has distinct pointed 'shoulders'. The pale end of the scutellum is pointed.
Brown shield bug, Dictyotus caenosus is a seed feeder. It is more rounded and a uniform mid brown colour with fine dark punctures and a network of dark lines on the forewings.
Adult Pittosporum shield bugs, Monteithiella humeralis, are mainly found on their host plants. The adults are dark brown with pale lateral areas on the pronotum. The basal half the fifth antennal segment is pale.
Fifth instar nymphs
The last nymphal stage of the Alpine brown soldier bug is mostly black and orange-red. The lateral edge of the pronotum is red. There is also a prominent red area by each wing bud and a pair of red areas near the end of the abdomen. The antennae have red on the basal two-thirds of segments 2, and red at the base of segment 3.
Brown soldier bug last nymphal stage of the is mostly black and white. The lateral edge of the pronotum is white and there are white marks on the lateral edges of the abdomen. There is also a prominent white area by the wing buds. The tibia of each leg has a white band. The antennae have red on segments 2, 3, and four. The fifth instar of the subspecies, C. nasalis turbotti, is shiny green instead of black. Nymphs of Australian Brown soldier bugs seen in photos are quite different from those illustrated here from around Auckland. Australian specimens are much redder.
Schellenberg's soldier bug last stage nymph is mainly black. There is a thin white lateral edge on the pronotum. On the abdomen there is prominent red area around a central black areas associated with the scent gland openings. The legs also have white bands on the tibia. The antennae are dark.
Brown shield bug last stage nymph has a dark grey-brown head and thorax. The abdomen is pale with numerous brown punctures. The areas around the scent gland openings are dark brown. The antennae are dark brown.
Pittosporum shield bugs last stage nymph is dark brown and has pale bands on the antennae. The nymphs are normally only found on host plants.
The black eggs are laid in batches of 14 or more. There are short white spines around the top of the eggs. Small batches of black eggs could be confused with parasitised eggs of other species of Pentatomidae.
Nothing is known about the natural enemies of the Alpine brown soldier bug. They may occasionally be eaten by birds, but the scent glands probably deter most would be predators. Wasp egg parasitoids are known for other soldier bugs and eggs of the Alpine soldier bugs may be affected by them.
There are no reports of the prey of Alpine brown soldier bugs. The Brown soldier bug has been observed feeding on a variety of free living prey, especially caterpillars.
Like other Hemiptera, the Alpine brown soldier bug has sucking mouth parts. The long stylets, special shaped rods, are held in the rostrum. The Alpine brown 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.
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.
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.
Anne Barrington and Sophie Hunt, Plant & Food Research for specimens to photograph.
1 December 2018. NA Martin. Changed symbol used for apostrophes.