Once thought to be extinct, 73 critically endangered Lord Howe Island Stick Insects hatched at the San Diego Zoo as part of an international breeding program to save these rare Australian insects.

Photo Credit:  Tammy Spratt/San Diego Zoo

Lord Howe Island Stick Insects – also known as Tree Lobsters – was believed to be extinct after rats invaded the Australian island from cargo ships in the 19^th century and ate all the insects.  But in the 1960s, scientists found one small colony – fewer than 40 individuals – living on a single shrub on a remote volcanic island off the coast of Australia.

From this fragile colony, scientists from the Melbourne Zoo collected a few individuals to begin a captive breeding program to save the species.  From those offspring, colonies were established at zoos around the world, including the San Diego Zoo, as insurance populations should a disease or natural disaster strike the original group.  The population has since grown to more than 9,000 individuals. 

Three hundred eggs went to the San Diego Zoo in January 2016, and the first 73 have hatched.  At this stage, the green insects are called “nymphs” and are experiencing their first “instar” or growth period between molts. They will molt their hard exoskeletons several more times, becoming darker each time, until they reach maturity at about seven months of age.  Adults are dark brown and measure five to six inches in length.   

Scientists hope to eventually reintroduce these insects to their former home on Lord Howe Island.