Lord Howe Island Stick Insect Facts

Scientific Name: Dryococelus australis

Lord Howe Island Stick Insect
Lord Howe Island Stick Insect.

Granitethighs / Wikimedia Commons / CC Attribution-Share Alike 3.0 Unported

Lord Howe Island stick insects are part of class Insecta and were once thought to be extinct until they were rediscovered in volcanic outcrops off the coast of Lord Howe Island. Their scientific name derives from a Greek word meaning “phantom.” Lord Howe Island stick insects are often referred to as lobsters due to their humongous size.

Fast Facts

  • Scientific Name: Dryococelus australis
  • Common Names: Tree Lobster, Ball’s Pyramid Insects
  • Order: Phasmida
  • Basic Animal Group: Insect
  • Distinguishing Characteristics: Large black bodies and claws resembling lobster claws
  • Size: Up to 5 inches
  • Life Span: 12 to 18 months
  • Diet: Melaleuca (Lord Howe Island plant)
  • Habitat: Coastal vegetation, sub-tropical forests
  • Population: 9 to 35 mature individuals
  • Conservation Status: Critically Endangered
  • Fun Fact: Lord Howe Island stick insects were rediscovered by a ranger who had heard rumors of large black bugs near Ball’s Pyramid in February of 2001.

Description

The Lord Howe Island stick insects are glossy black in color as adults and green or golden brown as juveniles. These flightless insects are active at night. Though neither sex can fly, they can run along the ground quickly. Males grow up to 4 inches, while females can grow up to almost 5 inches. Males have thicker antenna and thighs, but females have strong hooks on their legs and thicker bodies than males. Their large size for a bug has earned them the nickname “land lobsters.”

Lord Howe Island Stick Insect
Lord Howe Island stick insect (Dryococelus australis) at Melbourne Museum. Peter Halasz, WolfmanSF / Wikimedia Commons / CC Attribution-Share Alike 2.5 Generic

Habitat and Distribution

Lord Howe Island stick insects used to be found in the forests throughout Lord Howe Island, an island located a few miles off the coast of Australia. They were rediscovered on Ball’s pyramid, a volcanic outcrop off the shore of Lord Howe Island, where a tiny population of Lord Howe Island stick insects can be found. In the wild, they can live off Melaleuca (Lord Howe Island plant) among barren rock along a large slope.

Diet and Behavior

These insects are nocturnal bugs that feed on the leaves of Melaleuca at night and retreat to cavities formed by plant debris or the base of shrubs during the day. They huddle together during the day to protect themselves from predators. There can be as many as dozens of Lord Howe Island stick insects in one hiding spot. Juveniles, called nymphs, are active during the day and hide at night but slowly become nocturnal as they grow. Scientists are unsure if these insects ate anything else before they almost went extinct.

Reproduction and Offspring

A male will mate with a female one to three times through the night. Once the eggs are fertilized, the female leaves the tree or plant and pushes her abdomen into the soil to lay her eggs. She lays in batches of nine. The eggs are beige with raised patterns and are about 0.2 inches in size. Females can lay up to 300 eggs in their lifetime. Lord Howe Island stick insects are also capable of asexual reproduction, where unfertilized eggs hatch into females.

Lord Howe Island stick insect egg
BRISTOL, ENGLAND - SEPTEMBER 02: Mark Bushell, Curator of Invertebrates at Bristol Zoo, holds up an egg laid from a pair of critically endangered Lord Howe Island stick insects, one of the world's rarest insects, which were bred in captivity at Bristol Zoo Gardens on September 2, 2016 in Bristol, England.  Matt Cardy / Getty Images

The eggs incubate underground for 6.5 months before hatching. The nymphs transition from bright green to golden brown to black as they shed successive outer exoskeletons. At the same time, they become increasingly more active at night instead of the day. To protect themselves, nymphs camouflage themselves by mimicking small leaves swaying in the wind. Nymphs reach adulthood at about 7 months.

Threats

These land lobsters were brought to the brink of extinction due to humans and invasive species. They first saw rapid decline as fisherman used them as bait, but their biggest threat was the rat population that was introduced to the island in 1918 after a supply ship called the Mokambo ran aground. These rats voraciously ate the Lord Howe Island stick insects until they had virtually disappeared by the 1930s. Scientists speculate that they were able to survive by being carried by seabirds or vegetation to Ball’s Pyramid, where the harsh environment and secluded area allowed them to survive.

They are now being kept at the Melbourne Zoo. Scientists hope to reintroduce the Lord Howe Island stick insect to the mainland once the invasive rat species extermination is completed so that the insect can thrive in the wild once again.

pair of Lord Howe Island stick insects
A pair of critically endangered Lord Howe Island stick insects which were bred in captivity at Bristol Zoo Gardens on September 2, 2016 in Bristol, England.  Matt Cardy / Getty Images

Conservation Status

Lord Howe Island stick insects are designated as Critically Endangered by the International Union for Conservation of Nature (IUCN). They estimate the number of mature individuals in the wild to be between 9 and 35. Seven hundred individuals and thousands of eggs exist at the Melbourne Zoo, and Ball’s Pyramid has been preserved as part of the Lord Howe Permanent Park Preserve for scientific research only.

Sources

  • "Lord Howe Island Stick-Insect". IUCN Red List Of Threatened Species, 2017, https://www.iucnredlist.org/species/6852/21426226#conservation-actions.
  • "Lord Howe Island Stick Insect". San Diego Zoo, https://animals.sandiegozoo.org/animals/lord-howe-island-stick-insect.
  • "Lord Howe Island Stick Insect". Zoo Aquarium Association, https://www.zooaquarium.org.au/index.php/lord-howe-island-stick-insects/.
  • "Lord Howe Island Stick Insect". Zoos Victoria, https://www.zoo.org.au/fighting-extinction/local-threatened-species/lord-howe-island-stick-insect/.