Lord Howe Island Stick InsectScientific Name Dryococelus australis                            

Conservation Status Critically endangered

Appearance

Lord Howe Island stick insects are coloured a golden honey brown. Running down the abdomen is a faint cream stripe. Between each joint is a grey membrane. Males have thicker antenna and thighs than females along with a narrower abdomen. On the hind femurs of the males are two large spines.

Male’s measure up to 10.6cm (4in) long with females being slightly larger at 12cm (4.7in). They weigh about 25g (0.88 oz).

Lifespan                                                                                  

The lifespan of the Lord Howe Island stick insect is between 12 and 18 months.

Diet

Lord Howe Island stick insects are herbivores. One plant they are known to feed upon is the Lord Howe Island Melaleuca. They may feed upon a number of other species but their wild diet on Lord Howe Island is unknown.

Habitat

Ball’s pyramid, a small rocky outcrop in the Pacific ocean off the coast of New South Wales,, Australia is the only place where this species is found. Here they are confined to just one Lord Howe Island Melaleuca which sits amongst rocks.

Previously they lived on Lord Howe Island which is near Ball’s pyramid. Here they would nest during the day in hollows of the Lord Howe Island fig. Here there are a number of habitat types such as coastal vegetation, cloud forest and sub-tropical forests.

Reproduction

These animals have been found to form pair bonds on some occasions. A pair will sit side by side in a nest and the male will put three legs around the female. On other occasions pairs do not bond.

Following mating the female will deposit eggs that are about the size of a tic tac into the soil They begin white to pale cream but turn dark grey to black when they contact moisture. She begins laying the eggs about two weeks after hatching. This species may be able to reproduce pathenogenetically which means females is able to lay fertilized eggs without a male.

Eggs are laid in batches of 9-10 with a week between each. Over 300 eggs may be produced by a female over her lifetime.

Currently it is unknown how long it takes for an egg to hatch. Young stick insects (known as nymphs) are coloured bright green and measure 20mm (0.8in). In between hatching and adulthood they will moult five times.

Lord Howe Island Stick InsectMaturity is achieved at around seven months old.

Behavior

Nymphs are active during the day returning to their nests at night. As they grow they gradually become nocturnal.

Rescue efforts

The Lord Howe Island stick insect had been considered extinct since 1918. A ship ran aground on the island during the early 20th century leading to the introduction of black rats onto the island. These eventually decimated the stick insect population.

In 2001 a trip to a volcanic spire known as Ball’s pyramid made the discovery of a colony of just twenty stick Lord Howe Island Stick Insects.

During 2003 a group went to the pyramid and brought back two breeding pairs of Lord Howe Island Stick Insects to be housed at two mainland collections.

One of these, Melbourne Zoo, has so far bred 9,000 of these insects. Their intention is that this insurance population will be reintroduced to Lord Howe Island once the rats have been eradicated.

Quick facts

This species is known as ‘the world’s rarest insect.’

Photo Credits:

Top “Dryococelus australis 02 Pengo”. Licensed under CC BY-SA 3.0 via Wikimedia Commons – http://commons.wikimedia.org/wiki/File:Dryococelus_australis_02_Pengo.jpg#/media/File:Dryococelus_australis_02_Pengo.jpg

Bottom By Granitethighs (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

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