The lord howe island stick insect taxonomy and biology

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Common Name 


Lord Howe Island Stick Insect 

Scientific Name 


Dryococelus australis 

Order / Family 


Order Phasmida (Phasmatodea) 





Recent Synonyms  

Eurycantha australe 





Karabidion australe 

Other Common Names  Lord Howe Island Phasmid, Giant Lord Howe  

Island Stick Insect, Land Lobster 




1.1 Description 

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 

easily separated by two large spines on the hind femur of the male (which are 

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). 


1.2 Known 


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 

north-west face of Balls Pyramid. The melaleucas cover an area of about 30m 

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. 


1.3 Habitat 


Lord Howe Island is covered with a range of lush subtropical habitats, from 

cloud forest at the tops of the mountains to coastal vegetation on the dunes. 

The temperature on Lord Howe Island ranges from 15


C to 25


C throughout 

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 

range of temperatures. The humidity is also high due to its exposure to the 

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.  


1.4 General 



There is only one source of published information on LHISI habits in the wild. 

Lea (1916) noted that “During the day they remain concealed in hollows in 

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 

the hollows considerable numbers live together in all stages, but with 

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 outer foliage of melaleucas and are presumed to shelter during the day at 

the bases of the shrubs.  





1.5 Wild 



The diet of the stick insects on Lord Howe Island is not known, as no records 

were kept before they became extinct there. The only related published 

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 

LHISIs include: 

Blackbutt (Cryptocarya triplinervis) Maulwood 

(Olea paniculata

Greybark (Drypetes deplanchei ssp. affinis) Stinkwood 

(Coprosma putida

Sallywood (Lagunaria patersonia) Bullybush 

(Cassinia tenuifolia

Cotton wood (Celtis conferta ssp. amblyphylla) Sandalwood 

(Hibiscus tiliaceus

Dogwood (Omalanthus nutans (populifolius)) Hopwood 

(Dodonaea viscosa

Coprosma (Coprosma huttoniana) Goatwood 

(Coprosma prisca

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 

steel frame with wire mesh and a large door to enable potted plants or browse 

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 

water. There is no need to cover the top of the jar, as LHISIs generally do not 

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.  


The substrate is not important but a dish of free water should be available 

(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 

the roof of the enclosure in full sun, they will begin to seek daytime shelter as 

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 

mentioned below, females will push their abdomens into the substrate to 

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 

foliage at least once a day, or by provisioning enclosures with extra free water 

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 

this temperature range, and should preferably be kept between 20


 and 27



night and daytime temperatures respectively (appendix 9). The captive 

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 

temperature limits.  


Radiant heat, such as that from a radiator or boiler, is preferable to convective 

heat, such as that from a blow heater or reverse cycle air conditioner, as 

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. 


2.2 Cage 



As mentioned in 2.0, enclosures should be furnished with food plants, nesting 

boxes, a dish of free water, a source of humidity and, for the adults, an egg-

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 

materials such as plastic. It would also not be advisable to add plants that 

have not been tried successfully as food plants, without prior testing. 




3.1 Vet 



Veterinary procedures have been carried out on a number of adult LHISIs, 

each with different symptoms and different treatments. 


Case 1 

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 

goliath and Extatosoma tiaratum) x-rayed at the same time showed dozens of 

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 

light, and a solution of melaleuca leaves (mashed with a mortar and pestle), 

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 



Case 2 

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. 


Case 3 

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 

Ringer’s solution (see below), also without success. An x-ray revealed nine 

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. 


Case 4 

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 

condition inside, with a reasonable amount of fat, well spread throughout the 

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 

specimens, but the protozoa has not yet been identified (appendix 13) (or 

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 

Klepsiella pneumonia, but the significance of all these findings, and the 

cause(s) of the deaths are still unknown. 


Ringer’s solution 

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 

dramatically, that it is difficult to know where to start. Particularly when, for 

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 



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