One day in 1918, a supply ship, the S.S. Makambo from Britain, ran aground at Lord Howe Island and had to be evacuated. One passenger drowned. The rest were put ashore. It took nine days to repair the Makambo, and during that time, some black rats managed to get from the ship to the island, where they instantly discovered a delicious new rat food: giant stick insects. Two years later, the rats were everywhere and the tree lobsters were gone.
Totally gone. After 1920, there wasn’t a single sighting. By 1960, the Lord Howe stick insect, Dryococelus australis, was presumed extinct.
There was a rumor, though.