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San Diego Zoo Wildlife Alliance Working to Conserve Critically Endangered Lord Howe Island Stick Insect

Guests Can See These Rare Insects at Wildlife Explorers Basecamp at the San Diego Zoo

SAN DIEGO (Dec. 19, 2023) – For more than a decade, the San Diego Zoo Wildlife Alliance’s entomology team has collaborated with Australia’s Melbourne Zoo to maintain populations of the critically endangered Lord Howe Island stick insect. For the first time in North America, visitors to the San Diego Zoo will have the opportunity to see these rare, nocturnal insects in a specialized habitat at the Zoo’s Wildlife Explorers Basecamp.  

“We are honored to partner with Zoos Victoria on the conservation of the Lord Howe Island stick insect and beyond thrilled to be finally able to share these animals with our guests,” said Paige Howorth, McKinney Family director of invertebrate care and conservation, San Diego Zoo Wildlife Alliance. Added Howorth, “San Diego Zoo Wildlife Alliance is committed to invertebrate conservation, and bringing our guests close to this rare and iconic species is a great way to raise awareness for the lesser-known animals that run the world.  In so many ways—pollination, decomposition, predation, and simply as food for other animals—invertebrates make life possible for us all.” 

The Lord Howe Island stick insect breeding program at the San Diego Zoo is part of an ongoing, collaborative conservation effort to conserve the rarest insect on the planet—which was previously thought to be extinct on the island of the same name until a few individuals were rediscovered on a tiny nearby volcanic spire called Ball’s Pyramid in 2001. Upon the insect’s “rediscovery,” two pairs were brought to the Australian mainland for breeding—one to the Melbourne Zoo, which has successfully maintained this species in managed care and pioneered best practices for its recovery. The San Diego Zoo has partnered with Zoos Victoria/Melbourne Zoo since 2012 and is one of only two zoos outside of Australia and the only zoo in North America to work with this species. 

Sometimes called “tree lobsters”, the Lord Howe Island stick insect is a large, flightless, nocturnal insect that can grow up to 6 inches in length when fully mature. Since 2012, the Zoo has received eggs from Australia on three occasions and continues to build upon the knowledge and critical work initiated by the Melbourne Zoo. The stick insects are raised in the McKinney Family Invertebrate Propagation Center, within a dedicated quarantine facility. Temperature and humidity are closely controlled, and UV-transmissible skylights allow access to natural photoperiod cues. The eggs hatch into nymphs, which go through several molting stages for approximately seven months. Nymphs are bright green for the first few months of life. As they mature, they begin to darken to greenish-brown and seek shelter during daylight. Adults are a dark, glossy brown-black, and are strictly herbivorous, foraging at night on host plants and resting in tree hollows and other retreats during the day.  

In addition to the entomology team, the San Diego Zoo’s horticulture team also plays a pivotal role in the successful rearing of these insects. Early in the San Diego Zoo’s program, Zoo horticulturists traveled to Australia to collect seeds and cuttings of important host plants for young stick insects that were unavailable in North America. Adult stick insects have different host plant preferences and thrive on plants such as Moreton Bay fig and wooly tea tree, also grown at the Zoo. The Horticulture team now maintains a significant amount of plant material to support the large insurance population throughout all their life stages.  

Lord Howe Island stick insects are endemic to the Lord Howe Island Group, a cluster of volcanic islands in the Tasman Sea between Australia and New Zealand.  They are listed as Critically Endangered on the International Union for Conservation of Nature (IUCN) Red List of Threatened Species, and Critically Endangered under Australia’s Environment Protection and Biodiversity Act. They are threatened in their native habitat by the presence of invasive plants and non-native predators, including rats that originally extirpated them from Lord Howe Island. Their tiny habitat on Ball’s Pyramid supports extremely low numbers of the insect, is subject to catastrophic weather events and collectors, and the fragility and low abundance of the existing host plants is of critical concern.  Prior to the arrival of rats, the insects filled an important ecological role as primary consumers of plant material and food for other native wildlife.   

The Lord Howe Island Board and residents have been key partners in the decades-long preparation to one day return this animal to its ancestral home.  An unprecedented rat eradication effort has been diligently implemented since 2019, and an “ecological renaissance” has followed on the island, involving the reappearance of many other rare or presumed extinct plant and animal species that once fell prey to introduced rats.  The San Diego Zoo’s insurance population of Lord Howe Island stick insects provides security for the next stage of the conservation journey for this species, as plans progress to reestablish wild populations. 

Visitors to Wildlife Explorers Basecamp can see the new stick insect habitat in the Tree Hollow area of Spineless Marvels, Level 1.  They are maintained within a reversed light cycle so that guests can view them during the day under red light, which is invisible to the insects and simulates night, their active time. To learn more about San Diego Zoo Wildlife Alliance’s conservation efforts, visit sdzwa.org. 

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About San Diego Zoo Wildlife Alliance  
San Diego Zoo Wildlife Alliance is a nonprofit international conservation leader, committed to inspiring a passion for nature and working toward a world where all life thrives. The Alliance empowers people from around the globe to support their mission to conserve wildlife through innovation and partnerships. San Diego Zoo Wildlife Alliance supports cutting-edge conservation and brings the stories of their work back to the San Diego Zoo and San Diego Zoo Safari Park—giving millions of guests, in person and virtually, the opportunity to experience conservation in action. The work of San Diego Zoo Wildlife Alliance extends from San Diego to eco-regional conservation “hubs” across the globe, where their expertise and assets—including the renowned Wildlife Biodiversity Bank—are able to effectively align with hundreds of regional partners to improve outcomes for wildlife in more coordinated efforts. By leveraging these skills in wildlife care and conservation science, and through collaboration with hundreds of partners, San Diego Zoo Wildlife Alliance has reintroduced more than 44 endangered species to native habitats. Each year, San Diego Zoo Wildlife Alliance’s work reaches over 1 billion people in 150 countries via news media, social media, their websites, educational resources and the San Diego Zoo Wildlife Explorers television programming, which is in children’s hospitals in 13 countries. Success is made possible by the support of members, donors and guests to the San Diego Zoo and San Diego Zoo Safari Park, who are Wildlife Allies committed to ensuring all life thrives.