Dryococelus

File:Dryococelus australis 02b Pengo.jpg

Adult Lord Howe Island stick insects can measure up to {{convert|20|cm|0}} in length and weigh {{convert|25|g|0}}, with males 25% smaller than females. They are oblong in shape and have sturdy legs. Males have thicker thighs than females. Unlike most phasmida, the insects have no wings.

The behaviour of this stick insect is highly unusual for an insect species, in that the males and females form a bond in some pairs.{{cite journal|last1=Honan|first1=Patrick|title=Notes on the biology, captive management and conservation status of the Lord Howe Island Stick Insect (Dryococelus australis) (Phasmatodea)|journal=J. Insect Conserv.|volume=12|issue=3–4|pages=399–413|year= 2008|doi=10.1007/s10841-008-9162-5|s2cid=34793618}} The females lay eggs while hanging from branches. Hatching can happen up to nine months later. The nymphs are first bright green and active during the day, but as they mature, they turn black and become nocturnal.

Reproduction can happen without the presence of males (parthenogenesis) and this quality has allowed the species to survive when they are low in numbers.{{cite web |last=Mantle |first=Beth |date=24 January 2013 |title=Australian endangered species: Lord Howe Island stick insect |work=The Conversation |publisher=CSIRO |url=http://theconversation.com/australian-endangered-species-lord-howe-island-stick-insect-11789 |access-date=30 March 2013}}

The stick insects were once very common on Lord Howe Island, where they were used as bait in fishing.{{Cite web |last=Travers |first=Scott |title=Driven To ‘Extinction’ By A Shipwreck, A 2001 Discovery Brought The ‘World’s Rarest Insect’ Back To Life |url=https://www.forbes.com/sites/scotttravers/2025/01/06/driven-to-extinction-by-a-shipwreck-a-2001-discovery-brought-the-worlds-rarest-insect-back-to-life/ |access-date=2025-01-07 |website=Forbes |language=en}} They were believed to have become extinct soon after the supply ship {{ship|SS|Makambo}} ran aground on the island in 1918, allowing black rats to become established. After 1920, no stick insects could be found. The species was declared extinct.

However, in 1964, a team of climbers visiting Ball's Pyramid, a rocky sea stack {{convert|23|km}} south-east of Lord Howe, discovered a dead stick insect. In subsequent years, climbers found a few more fresh carcasses, but expeditions to find live specimens were unsuccessful.

In 2001, Australian scientists David Priddel and Nicholas Carlile hypothesised that there was sufficient vegetation on the islet to support a population of the insects, and, with two assistants, travelled there to investigate further. They scaled 120 metres of grassy, low-angled slope, but found only crickets. On their descent, the team discovered large insect droppings under a single Melaleuca shrub growing in a crevice approximately 100 metres above the shoreline. They deduced that they would need to return after dark, when the insects are active, to have the best chance of finding living specimens. Carlile returned with local ranger Dean Hiscox and, with a camera and flashlights, scrambled back up the slopes. They discovered a small population of 24 insects living beneath the Melaleuca shrub amongst a substantial build-up of plant debris.{{cite journal |last1=Priddel |first1=D. |last2=Carlile |first2=N. |last3=Humphrey |first3=M. |last4=Fellenberg |first4=S. |last5=Hiscox |first5=D. |date=July 2003 |title=Rediscovery of the 'extinct' Lord Howe Island stick-insect (Dryococelus australis (Montrouzier)) (Phasmatodea) and recommendations for its conservation |journal=Biodiversity and Conservation |doi=10.1023/A:1023625710011 |volume=12 |issue=7 |pages=1391–1403|s2cid=20545768 }}{{cite web|last=Krulwich|first=Robert|author-link=Robert Krulwich|date=18 January 2016|orig-year=29 February 2012|title=Six Legged Giant Finds Secret Hideaway for 80 years|url=https://www.npr.org/sections/krulwich/2012/02/24/147367644/six-legged-giant-finds-secret-hideaway-hides-for-80-years|url-status=live|access-date=16 May 2021|publisher=National Public Radio|archive-url=https://web.archive.org/web/20150520015242/http://www.npr.org:80/sections/krulwich/2012/02/24/147367644/six-legged-giant-finds-secret-hideaway-hides-for-80-years? |archive-date=2015-05-20 }}

In 2003, a research team from New South Wales National Parks and Wildlife Service returned to Ball's Pyramid and collected two breeding pairs, one destined for a private breeder in Sydney and the other sent to the Melbourne Zoo.

After initial difficulties, the insects were successfully bred in captivity in Melbourne. The ultimate goal was to produce a large population for reintroduction to Lord Howe Island, provided that a project to eradicate the invasive rats was successful. In 2006, the captive population of insects numbered about 50 individuals, with thousands of eggs still to hatch. In 2008, when Jane Goodall visited the zoo, the population had grown to 11,376 eggs and 700 individuals, 20 of which were soon after returned to a special habitat on Lord Howe Island.{{cite web |last=Lewis |first=Martin W. |date=3 August 2010 |title=Lord Howe Island: Return of the Tree Lobster |publisher=Geocurrents.info |url=http://geocurrents.info/place/australia-and-pacific/lord-howe-island-return-of-the-tree-lobster |access-date=29 February 2012}} {{As of|2012|April}}, the Melbourne Zoo had reportedly bred over 9,000 of the insects,{{cite web |title=Act Wild for Lord Howe Island Stick Insects |publisher=Zoos Victoria |url=https://www.youtube.com/watch?v=Eg3dcYJ2oI4 |access-date=5 November 2012}} including 1,000 adult insects, plus 20,000 eggs.

In 2012, the Budapest Zoo was the first zoo outside of Australia to reproduce the insects.{{cite news|title=Fotó: a világ legritkább rovarja kelt ki a fővárosi állatkertben|trans-title=Photo: the rarest insect in the world hatched at the Budapest Zoo|date=21 April 2012 |website=HVG.hu |lang=hu |url=https://hvg.hu/tudomany/20120421_legritkabb_rovar}}

In 2014, an unauthorised climbing team sighted live stick insects near the summit of Ball's Pyramid, in a thicket of sedge plants rooted in very thin soils at an altitude of 500 metres, suggesting that the insect's range on the island is more widespread than previously thought, and that its food preferences are not limited to Melaleuca howeana.{{cite book|author=Smith, Jim |year=2016|title=South Pacific Pinnacle, The exploration of Ball's Pyramid|publisher=Den Fenella press|isbn=978-0-9943872-0-2}}

By the beginning of 2016, Melbourne Zoo had hatched 13,000 eggs, and had also sent eggs to the Bristol Zoo in England, the San Diego Zoo in the United States, and the Toronto Zoo in Canada, to establish distinct insurance populations.{{cite news |date=13 January 2016 |title=Revived Aus stick insect takes on world |author=AAP |publisher=NineMSN |url=http://www.9news.com.au/national/2016/01/13/16/52/revived-aus-stick-insect-takes-on-world |access-date=13 January 2016}}

In 2018 it was announced that the CEO of the Lord Howe Island Board had approved a plan to exterminate the black rat population on Lord Howe Island to protect the island ecology and potentially reintroduce D. australis.{{Cite news|date=2017-10-05|title='Extinct' tree lobster officially back from dead as Lord Howe pushes ahead with poison program|url=https://www.abc.net.au/news/science/2017-10-06/extinct-lord-howe-stick-insect-back-from-dead/8984902|access-date=2021-05-17|website=www.abc.net.au|language=en-AU}} {{As of|2023}} plans are being made to reintroduce the insects to Blackburn Island, an islet in the Lord Howe lagoon, to test the potential for reintroduction to the larger island.{{cite web |last1=Warne |first1=Kennedy |title=Rats invaded paradise. Here’s how paradise fought back. |url=https://www.nationalgeographic.com/premium/article/rodents-rats-eradicated-tropical-paradise-australia-island |website=National Geographic |access-date=8 March 2024 |language=en |date=18 April 2023}}

In 2025, the Prague Zoo joined the conservation program. The zoo became the sixth institution in the world to create living conditions for D. australis and the third to put them on display.{{Cite web |last=Janicek |first=Karel |title=Prague Zoo joins the effort to ensure the survival of a rare insect once considered extinct |url=https://phys.org/news/2025-04-prague-zoo-effort-survival-rare.html |access-date=2025-04-11 |website=phys.org |language=en}} The new "Ball’s Pyramid exhibit" also includes greenhouses and garden beds for cultivating the plants used to feed the insects.{{Cite web |title=Ball’s Pyramid |url=https://www.zoopraha.cz/en/pyramid |access-date=2025-04-11 |website=Prague Zoo |language=en-gb}}

A 2017 study comparing DNA sequences of phasmids originating from Ball's Pyramid with those from museum specimens from Lord Howe Island showed that the Ball's Pyramid sequences differ from those of Lord Howe Island by a degree comparable to variation within the museum specimens, despite some morphological differences between the two groups.{{Cite news |title='Extinct' tree lobster back from the dead in Australia |url=https://au.news.yahoo.com/tree-lobster-found-on-remote-australian-island-not-extinct-37373359.html |access-date=2021-05-18 |website=au.news.yahoo.com |language=en-AU}} This confirms that the two populations represent the same species. The genome was found to be very large in size (over 4 Gb) and is probably hexaploid.{{cite journal |last1=Mikheyev |first1=A. S. |last2=Zwick |first2=A. |last3=Magrath |first3=M. J. L. |last4=Grau |first4=M. L. |last5=Qiu |first5=L. |last6=Su |first6=Y. N. |last7=Yeates |first7=D. |year=2017 |title=Museum Genomics Confirms that the Lord Howe Island Stick Insect Survived Extinction |journal=Current Biology |volume=27 |issue=20 |pages=3157–3161.e4 |doi=10.1016/j.cub.2017.08.058 |pmid=28988864 |doi-access=free}}

• Giant weta
• Lazarus taxon
• Threatened fauna of Australia

{{Reflist|2}}

• {{Wikispecies-inline|Dryococelus australis|Dryococelus australis}}
• {{Commons category-inline}}
• [https://vimeo.com/76647062 Sticky, a short film on the rediscovery of the Lord Howe Island Stick Insect]
• [http://blogs.scientificamerican.com/video-of-the-week/2012/08/22/hatching-of-the-lord-howe-island-stick-insect/ Video of Stick insect hatching]
• [https://web.archive.org/web/20070109023343/http://www.fnpw.org.au/enews2/Phasmids.htm The Lord Howe Island Phasmid: an extinct species reborn] by David Priddel, at the Foundation for National Parks & Wildlife
• [http://www.smh.com.au/articles/2003/10/18/1066364522158.html Sticks and stones] article, Sydney Morning Herald, 18 October 2003 (with picture)
• [http://www.abc.net.au/science/news/stories/s245820.htm Giant stick insect rediscovered], science news 14 February 2001 at the Australian Broadcasting Corporation

• [http://rspb.royalsocietypublishing.org/content/276/1659/1055.abstract Phylogenetic study on Dryococelus australis]

{{Taxonbar|from1=Q14626919}}

Category:Phasmatidae

Category:Monotypic insect genera

Category:Insects of Lord Howe Island

Category:Critically endangered insects

Category:Insects described in 1855

Category:Insects of Australia

Category:Phasmatodea genera