First 'Tree Lobsters' Born in the U.S. Hatch at San Diego Zoo

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Tree lobsters can grow to over a half-foot in length. Peter Halasz/Wiki Commons

Never heard of tree lobsters? These giant stick insects are among the largest bugs in the world, capable of growing to over 6 inches in length. They're also among the rarest insects on Earth, and the harrowing story of their survival and conservation is a real tear-jerker, even if you're not usually a fan of giant creepy-crawlies.

Tree lobsters, also called Lord Howe Island stick insects (Dryococelus australis), are a species endemic to the remote Lord Howe Island Group, an irregularly shaped volcanic remnant in the Tasman Sea between Australia and New Zealand. The bug's size is a dramatic example of island gigantism, a biological phenomenon in which some creatures isolated on small islands evolve to mammoth proportions compared to their mainland relatives.

For much of this species' existence, it had no major predators. But after a ship ran aground on the island in 1918, black rats were introduced. By 1920 — just two years later — the tree lobster was officially wiped out. The entire species was presumed extinct.

Then, in the 1960s, a team of climbers visited Ball's Pyramid, a treacherous rocky sea stack about 14 miles southeast of Lord Howe Island. This rocky isle is not exactly habitable, with no free water and little vegetation, but the climbers found something unusual: the corpse of a monster stick insect. This dead animal was later confirmed to be a tree lobster, reviving hopes that maybe a few survivors had found refuge on this isolated rock.

It wasn't until 2001, more than 80 years since the last tree lobster had been seen alive, that a pair of Australian scientists decided to travel to Ball's Pyramid to search for a long lost population of these remarkable beasties. They scaled 500 feet up the sharply angled rock face and found nothing. Then, on their descent, a glimmer of hope: large insect droppings underneath a single shrub.

Since tree lobsters are known to be active at night, the team returned to the spot later that evening. They pulled back the shrub, and in a remarkable moment found themselves witness to the last 24 tree lobsters on Earth, all bundled up and living within the tiny crevice under the shrub.

The discovery was an immediate sensation, reported worldwide. "It was a massive, massive PR event for insects," Paige Howorth, curator of entomology at the San Diego Zoo, told NPR, "especially an insect like this, which is not one you would deem charismatic, you know, for the most part."

Two breeding pairs were later collected from the small group so that scientists could attempt to breed them and revive their population. Today, more than 1,000 adult tree lobsters have been successfully raised by a team at the Melbourne Zoo, with the hope of eventually reintroducing them back to Lord Howe Island. It's one of conservation's greatest, and most moving success stories.

"It's a very romantic story, in that there's always that hope that one day, they may go home," said Rohan Cleave, zookeeper in Melbourne.

For all the success that Melbourne Zoo has had, however, other zoos around the world have had a difficult time with their own breeding programs. That is, until now. San Diego Zoo staffers recently announced that they have successfully hatched the first tree lobsters born in the United States, fantastic news for the future of this large but charismatic bug.

"The nymphs seem to emerge from the egg overnight or in the very early morning hours," said Howorth. "Most mornings since Saturday have included one or two little green surprises. We couldn't be happier!"

You can view a remarkable film of a tree lobster hatching here:

One of the more charming traits of tree lobsters is that they sleep in pairs, and spoon. Males wrap their six legs protectively around the female as they snooze. Perhaps it's a remnant behavior leftover from their many years hanging precariously to existence within that crevice on Ball's Pyramid. Or maybe it's this bonding behavior that has kept them alive for so long in the first place.

At least for now, there's finally reason to hope for this endearing species, back from the brink of extinction.