Lord Howe Island Stick Insect
Order Phasmida (Phasmatodea)
Island Stick Insect, Land Lobster
The Lord Howe Island Stick Insect (LHISI) is a large, flightless phasmid, with
males reaching 120mm (more commonly 106mm) at adulthood and females
150mm (more commonly 120mm). Both sexes are black on maturity, often
with a reddish-brown tinge. The body is generally smooth and shiny, and the
membranous areas between joints are pale grey (appendix 1).
A number of features distinguish adult males from females, but they can be
absent in the female), and by the shape and length of the last segment of the
abdomen (appendix 2). Females have a long, pointed ovipositor sheath
underneath the last segment, which is absent in the males (appendix 3).
Females also have a wider and more terminally tapering abdomen than
Upon hatching, LHISIs are pale to mid-green, and become darker green as
they moult. Juveniles are pale brown, becoming darker brown with age, then
very dark brown to black in the final instars (appendix 4).
LHISIs were once common on Lord Howe Island but became extinct soon
after rats were introduced in 1918. They were presumed extinct until
rediscovered on Balls Pyramid in 2001. Balls Pyramid is the tip of a sea
mount, 25km southeast of Lord Howe Island (appendix 5).
The only known range of LHISIs is amongst a group of melaleucas on the
by 10m, and are the only vegetation on the pyramid other than groundcovers.
Smaller islands around Lord Howe Island have been extensively searched for
LHISIs, without success.
Lord Howe Island is covered with a range of lush subtropical habitats, from
The temperature on Lord Howe Island ranges from 15
C to 25
the year (appendix 6), and the humidity is generally high year round. There is
a great range of plant species throughout the habitats in which LHISIs were
once known to occur, but on much of the island the largest tree is the Lord
Howe Island Fig (Ficus macrophylla columnaris). In the forested areas, the
canopy is high and there may be little lower level vegetation or ground cover,
and the soil is deep and often sandy.
Balls Pyramid is much more exposed than Lord Howe Island, with a greater
sea, but the rock itself is very dry and there are no sources of fresh water.
Consequently there is very little vegetation and almost no soil. The
melaleucas on which the LHISIs survive are very old and stunted, and
growing very densely close to the rock. Due to the large numbers of sea birds
which nest on the bushes, the foliage is covered with guano, and many of the
plants are also being threatened with smothering from Morning Glory (Ipomea
indica). There are quantities of melaleuca leaf litter at the bases of the
bushes, in some places quite deep, but this is very friable and dry.
There is only one source of published information on LHISI habits in the wild.
upright or slightly sloping stems of living trees, but their presence may be
detected by examining the ground at the foot of the trees, where heaps of
their excrement may be found. The hollows are seldom less than eighteen
inches in length, and are sometimes much longer…On examining the heaps
of droppings, frequently both fresh and newly-hatched eggs may be found, the
females simply extruding their eggs as soon as these are ready.
“They appear to come out late at night to climb the trees directly for food. In
immature forms in the majority; from one hollow that was completely emptied
sixty-eight specimens were taken; in the same hollow were several large
spiders and cockroaches…In nearly all cases that I examined it was seen
plainly that the phasmas had selected for their domicile trees that had been
largely bored by larvae of a large longicorn beetle.”
In the wild on Balls Pyramid, LHISIs are known to emerge at night to feed on
the bases of the shrubs.
The diet of the stick insects on Lord Howe Island is not known, as no records
information is that juvenile LHISIs were found in large numbers during the day
in hollows of tree trunks, presumably of the dominant Lord Howe Island Figs
(Ficus macrophylla columnaris). On Balls Pyramid, they are known to feed on
Lord Howe Island Melaleuca (Melaleuca howeana), but they may have other
additional plant sources there.
Other plants occurring on Lord Howe Island which may have been eaten by
Blackbutt (Cryptocarya triplinervis) Maulwood
Greybark (Drypetes deplanchei ssp. affinis) Stinkwood
Sallywood (Lagunaria patersonia) Bullybush
Cotton wood (Celtis conferta ssp. amblyphylla) Sandalwood
Dogwood (Omalanthus nutans (populifolius)) Hopwood
Coprosma (Coprosma huttoniana) Goatwood
Coprosma (Coprosma lanceolaris)
Kentia palm (Howea forsteriana)
Coprosma (Coprosma inopinata)
Housing: Exhibit & Off Exhibit (for both larval and adult stages)
Young LHISI nymphs may be housed together in large numbers (up to 80 per
enclosure) as long as sufficient food is available. The nymphs clump together
on the roof of the enclosure during the day, piled four or five deep, and move
out to feed individually at night.
The enclosure may be composed of a wooden, recycled plastic, aluminium or
to be easily changed (appendix 7). Care should be taken if using recycled
plastic, as there is some evidence of toxicity from the plastic at high
temperatures. The mesh should be large enough to allow airflow, and small
enough to maintain humidity within the enclosure. There should be no gaps in
the enclosure larger than 2mm. The minimum sized enclosure for a large
group of nymphs is approximately 700mm cubed.
The enclosure should contain a potted food plant or cut browse in a jar of
drown themselves as other insects do, except for very small nymphs on very
rare occasions. The plants should touch at least one side and preferably the
top of the enclosure at some point, but there should be sufficient space under
the roof for the nymphs to hang whilst moulting unobstructed by the plants.
(although this species has not been observed drinking free water, closely
related species in New Guinea has been regularly observed to do so) and a
petri dish full of water, changed weekly or every few days, is sufficient. If
humidity is low, a piece of bark, tree fern or palm trunk soaked daily in water
should be supplied.
Although young nymphs do not shelter during the day and will choose to sit on
they mature, particularly as their colouring starts to darken to brown and then
black. Consequently, a small ‘nesting box’ is required in the enclosures. The
nesting box may be a hollowed log with a lid, a hollowed-out tree fern trunk,
two coconut fibre hanging basket linings sewn together to form a ‘drey’, or a
wooden nesting box used for finches etc. The latter is the most convenient
and easiest to use, with a hole in the side for access and a hinged lid for
inspection and cleaning. A nesting box 280mm long, 125mm wide and 120mm
deep, with a 45mm diameter hole in the side and a hinged lid will house
approximately 10 adults or 40 nymphs (appendix 8).
Adult LHISIs require similar enclosures to nymphs, but need more space per
individual. An enclosure 700mm cubed will house approximately 10 adults.
They will appreciate more space if available, and will happily live ‘free range’
in an entire glasshouse if given the opportunity. As with the nymphs, food
plants, a dish of free water, at least one nesting box and water-soaked bark
should also be supplied.
Once females begin laying eggs, egg-laying substrate should be provided. As
deposit an egg, so a container at least 60mm deep filled with moist sand is
required. A Tupperware container approximately 300mm wide by 220mm long
by 100mm deep will cater for a number of females, but even a small
rectangular Chinese takeaway container will suffice. Breeders of the closely
related Thorny Stick Insect (Eurycantha calcarata) cover the base of the
enclosure with peat moss in which the insects lay eggs, but this method has
not been tried with LHISIs.
Housing Conditions (for both larval and adult stages)
Housing conditions are paramount for this species. The humidity should be
high, with a minimum of 50%RH, preferably 70%RH, both day and night. They
seem to do best when the humidity is between 80 and 95%RH (appendix 9).
Air flow created by heating should not be allowed to directly affect the LHISI
enclosures, as a continuous flow of warm air will dry out the enclosures and
desiccate the insects. Humidity can be provided by domestic or even industrial
humidifiers (if available), by steamers if the holding area is small, or by
continuously boiling large urns in larger holding areas. Humidity can also be
increased by using smaller mesh sizes on the enclosures, by spraying the
or water-soaked material such as bark.
The temperature on Lord Howe Island is never lower than 15
C or higher than
C. This species should therefore not be kept for extended periods outside
population is descended from a population on Balls Pyramid, which is more
exposed and has a greater temperature range than that on Lord Howe Island,
so theoretically captive LHISIs should also be able to tolerate a greater range,
but so far the captive population has been kept within the narrower
Radiant heat, such as that from a radiator or boiler, is preferable to convective
radiant heat will not dry out the holding area as much. The type of cooling is
not as important, as cool air blown over the enclosures will not dry them out
as much as warm air will. If the enclosures are well insulated and kept within a
larger holding space such as a glasshouse, it should be remembered that the
temperature and humidity in the glasshouse will not necessarily be the same
as that within the enclosures, but that the difference may be consistent and
one can in this case be used as a guide for the other (appendix 10).
LHISI nymphs are diurnal and adults nocturnal, so both should be kept under
separate lighting regimes. Nymphs can be kept in direct sunlight as long as
the temperature remains moderate, or under fully artificial lighting. Some
natural light may be beneficial for the nymphs and is certainly beneficial for
the foodplants, particularly potted ones. Adults can be kept under a natural
daily light cycle or a reversed cycle, and extraneous lighting should be kept to
a minimum, both day and night. As adults do not appear to see red light, red
globes can be fitted as lighting or used in torches without affecting the insects’
Temperature and humidity in particular should be monitored at least daily.
This can be recorded manually using thermometers and relative humidity
readers with conversion sheets, and preferably digitally with data loggers as
well. Temperature and humidity (along with genetic management and food
plants) are probably the two most important factors in maintaining a
successful population of LHISIs.
As mentioned in 2.0, enclosures should be furnished with food plants, nesting
laying substrate. A range of other furnishings may be added, particularly if the
species is being displayed, but there has been evidence of adults chewing
have not been tried successfully as food plants, without prior testing.
Veterinary procedures have been carried out on a number of adult LHISIs,
The female originally collected from Balls Pyramid ceased feeding and started
to become inactive about a week after being in captivity, following an episode
of egg laying. Over several days her activity, particularly feeding activity, was
notably reduced and for five days she ceased feeding altogether. During this
period she was x-rayed to determine if she was egg bound due to a possibly
inappropriate egg-laying substrate, and six eggs were clearly seen inside her
abdomen (appendix 11). These egg were subsequently deposited by the
female and later developed very thin, brittle shells, and eventually
disintegrated entirely, presumably due to the effects of the x-ray, but all further
eggs appeared undamaged. Other analogous stick insects (Eurycnema
eggs in the abdomen, so the LHISI female was apparently not egg bound. Her
foregut was also seen in the x-ray to be full of air, suggesting aerophagy, a
sign of distress in vertebrates, particularly birds (appendix 11).
After five days she became completely immobile and unreactive to touch or
glucose and calcium in distilled water was administered to her with an
eyedropper on her mouthparts. Within a few hours, she became active again
and resumed normal activity, subsequently living for another year. The cause
of her morbidity and the reasons for the success of the treatment are still
An adult male was found dead unexpectedly and autopsied by Melbourne Zoo
vets. Upon dissection, his foregut was full of newly chewed leaves, his hindgut
full of well-processed leaf material, his testes well-developed and plenty of fat
throughout the body, suggesting a healthy condition and that he was feeding
well right up to the point of death. However, his internal organs appeared very
dry, with almost no free fluid in the body cavity, suggesting general
desiccation. The enclosure in which he was being kept was moved off the
floor to an area in the glasshouse where humidity was higher, the mesh of the
enclosure was changed for a smaller mesh size, and humidity was increased
in the glasshouse throughout the night. There have been no subsequent
deaths attributable to desiccation.
An adult female was found near death and the treatment used in case 1 was
attempted, without success. The vets also administered a modified form of
well-developed eggs in her abdomen, and like case 1, signs of aerophagy.
Upon dissection, the foregut was found to be stretched like a balloon full of air,
and the foregut was almost empty, suggesting she hadn’t eaten for some
time. There was a reasonable spread of fat throughout her body, but not as
much as seen in previously dissected specimens (appendix 12). On the inside
of the gut, at the junction of the fore- and hindgut was a small area of green
pigment, which appeared to be part of, or embedded in, the gut wall. This was
analysed by pathologists without result. The pigment may have come from a
pelletised fertilizer used on the potted melaleuca plants, as the colour was
identical to that of Greenjacket Osmocote, perhaps consumed inadvertently
by the female. Greenjacket Osmocote has been removed from the potting mix
and there have been no subsequent cases attributable to this.
Nine adult LHISIs were found dead in a single enclosure one morning, with no
surviving specimens in that enclosure. Seven appeared to have died whilst
feeding, as they were lying upside down at the base of the plant, and two
were found dead inside the nesting box. The food plant was tested for
insecticide and herbicide but none was found.
Autopsies were conducted on the insects and all had fair to poor body
abdomen, but not as much as seen in previous specimens. All specimens had
some air in the foregut without any food present, and very little food in the
hindgut. The hindgut contained mostly brown liquid, which was also found on
the floor of the enclosure, with some semi-solid material and some air
bubbles. The overall colour of the internal organs was duller than that seen
Pathology found possible protozoan parasites in the wall of the gut of several
even confirmed as protozoa by a specialist). There was also heavy growth of
certain bacteria and fungi in the gut (also unidentified) and analysis of whole
mounts of the insects’ heads found a type of ulceration or lesion associated
with fragmentation of the cuticle (appendix 14) and the presence of
spirochaetes (appendix 15). Swabs of the nesting boxes found the bacteria
cause(s) of the deaths are still unknown.
Ringer’s solution is used generally by vets for therapeutic support of
dehydrated or distressed vertebrates. Several attempts have been made over
the years by a number of breeders to modify this solution for invertebrates,
particularly tarantulas. Some studies have also been done on the physiology
of stick insects, particularly comparisons between the mineral (and other)
components of their food plants, and the components of the stick insects’
bodies. The vets at Melbourne Zoo have attempted to modify Ringer’s solution
to cater for the differences between vertebrates and stick insects, but there is
so little research available, and the results that have been published vary so
example, papers published on the quantities of magnesium found in the
bodies of stick insects vary by orders of magnitude between different species.
We have attempted to administer a version of Ringer’s solution intravenously
(intracoelomically) to unwell specimens through membranes between tergites
in the abdomen, but so far without success.
Adults and nymphs can be euthanased by placing them in a container in the
freezer for at least four hours. They can then be removed from the freezer and
dried for mounting. If adults are to be preserved in alcohol, they should be
injected with at least 90% ethanol and then submerged in a jar filled with