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New Zealand Wetwood Termites

Insect: Stolotermes ruficeps Brauer and Stolotermes inopinus Gay (Isoptera: Termopsidae) (Fig. 1)


Forest and Timber Insects in New Zealand No. 60
 
 
Based on R.H. Milligan (1984)


Fig. 1 - Reproductives of Stolotermes ruficeps which have shed their wings.
 
Type of injury
Stolotermes ruficeps establishes colonies in moist, partially decayed wood. The galleries (Fig. 2)
are predominately longitudinal, irregular in cross section, and interconnected by narrow, almost
cylindrical passageways. Longitudinal plates of intact wood often partially divide larger cavities.
Stolotermes inopinus occupies rather drier, sounder material than Stolotermes ruficeps.
 
 
Fig. 2 - Workings of Stolotermes ruficeps in decaying radiata pine log.
 
Hosts
Colonies of Stolotermes ruficeps are found in dead and decaying standing trees, branch stubs,
logs and stumps of a wide variety of native hosts including Agathis australis (kauri), Dacrydium
cupressinum (rimu), Griselinia littoralis (broadleaf), Metrosideros robusta (northern rata),
Nothofagus (beech), and Podocarpus. Exotic hosts recorded include Chamaecyparis lawsoniana
(Lawson cypress), Cupressus lusitanica (Mexican cypress), Cupressus macrocarpa
(macrocarpa), Eucalyptus (eucalypts), Larix decidua (European larch) Salix (willow). Probably
decaying wood of any species of tree grown in New Zealand can be successfully attacked.
Although Stolotermes ruficeps occurs in decaying branch stubs of living plantation-grown Pinus
radiata (radiata pine) and other Pinus (pine) species, it has never been found in the heartwood.
Stolotermes inopinus is known from dead Pinus and Cupressus macrocarpa, and a dead stump of
Nothofagus.
 
Distribution
Stolotermes ruficeps is a native insect which occurs throughout New Zealand, principally in
forests. 
 
Stolotermes inopinus is also a native insect but only a few colonies have been discovered since it
was first recognised in 1969 from specimens collected near Eastbourne (Wellington). It has
subsequently been found at Whangarei, at Tangiteroria near Dargaville, in Woodhill Forest near
Helensville, and in Waipoua Forest. So few colonies have been discovered that little is known
about the biology of this species.
 
Economic importance
Only occasionally has Stolotermes ruficeps been recorded as attacking timber in use and then
only under damp conditions. Sound timber is damaged only when it is adjacent to decaying
material. Pine logs with termites in branch stubs have to be refused export unless they are
fumigated immediately before shipping. Stolotermes inopinus is likely to be of similar slight
economic importance.
 
Description
The constitution of the colony and castes of Stolotermes ruficeps(and presumably of Stolotermes
inopinus) are the same as for Kalotermes brouni (Milligan 1984). 
 
 
Fig. 3 - Winged reproductives of (left) Stolotermes ruficeps (length 12 mm) and (right)
Stolotermes inopinus (length 15 mm). The head and antanae of Stolotermes inopinus became
folded under when the specimen died.
 
Winged reproductives of Stolotermes ruficeps (Fig 3) are dark brown to black and about 12 mm
in length. The head is almost spherical and bears moderately long, slender antennae. The
segment immediately behind the head is narrower than the head. The wings are dark, about twice
as long as the body, and are folded flat over the abdomen when at rest. Nymphs resemble the
winged reproductives except that they are white to pale yellow and, in their later stages of
development, have external wing buds rather than wings. Fully grown nymphs are 8-9 mm long.
Soldiers (Fig.4) have oblong-shaped heads which are orange at the rear but distinctly darker at
the front, and two fifths as long as the body. Their jaws are about one-third as long as their head.
Soldiers do not have wing buds.
 
The winged reproductives (Fig.3) and soldiers of S. inopinus are similar in appearance to but
much larger in size than S. ruficeps.
 
 
Fig.4 - Nymphs and 2 soldiers (with coloured heads and large jaws) of Stolotermes ruficeps. 
 
Life history and habits
Winged reproductives of Stolotermes ruficeps swarm in autumn, but very few (no more than
about 3%) appear to fly further than 30 m. Most shed their wings immediately and move to
shelter in cracks and holes in the log from which they emerged (Fig. 1). 
 
To cast a wing Stolotermes ruficeps throws it forward over its head so that the wing bends or
breaks along the basal line of weakness, and then brushes it off by turning round and round, or
rubbing up against nearby objects. The same method is used for each wing in turn and all are
discarded within a few minutes. Whereas Kalotermes brouni reproductives may fly and land
several times before shedding their wings, Stolotermes ruficeps reproductives usually cast their
wings soon after the first flight. There appears to be little pairing of the sexes before attempts to
re-enter the wood are made. New colonies are formed when a male and female enter suitable
material by the same crack or hole and mate. The pair extend their workings and the first eggs
are laid in the following spring. Eggs take 33-35 days to hatch.
 
The first nymphs to emerge are fed by the parents, and later start to function as a worker caste.
They extend and maintain the galleries, pack faecal pellets into abandoned parts of the workings,
and feed younger nymphs, soldiers, and the queen. The workers also occasionally construct
surface tunnels or tubes of cemented soil, faecal pellets, wood particles, and other detritus to
protect themselves when passing from an established colony to new feeding grounds. 
 
A colony usually consists of between 50 and 250 termites, most of which will be nymphs, but if
the host material is suitable a colony may grow to about 3000 individuals and subcolonies
connected to the initial one may be formed. Growth of a colony may continue for 3 or more
years before any mature nymphs complete their development to winged reproductives and
swarm.
 
Presumably the development of colonies of Stolotermes inopinus is similar to that of Stolotermes
ruficeps but no study of this has been made.
 
Controls: Since these insects are of little economic importance, no control measures are needed.
 
References
Bain J.; Jenkin, M.J. 1983: Kalotermes banksiae, Glyptotermes brevicomis and other termites
(Isoptera) in New Zealand. New Zealand Entomologist 7: 365-371. 
Gay, F.J. 1969: A new species of Stolotermes (Isoptera: Termopsidae: Stolotermitinae) from
New Zealand. New Zealand Joumal of Science 12: 748-753. 
Kelsey, J. M. 1944: The identification of termites in New Zealand. New Zealand Joumal of
Science and Technology 25B: 231-260. 
Kelsey, J. M. 1946: Insects attacking milled timber, poles and posts in New Zealand. New
Zealand Journal of Science and Technology 28B: 65-1 00. 
Miligan, R.H. 1984: Kalotermes brouni Froggart (Isoptera: Termopsidae), New Zealand
drywood termites. New Zealand Forest Service, Forest and Timber Insects in New Zealand No.
59.
Miligan, R.H. 1984: Stolotermes ruficeps Brauer, Stolotermes inopinus Gay (Isoptera:
Termopsidae), New Zealand wetwood termites. New Zealand Forest Service, Forest and Timber
Insects in New Zealand No. 60.
Morgan, F. D. 1959: The ecology and external morphology of Stolotermes ruficeps.
Transactions of the Royal Society of New Zealand 86: 155-195.
 
Compiled: 1984