Stick insects, which live in remote regions predominantly in southeastern Asia and tend to be most (which isn't to say very) active at night, not to mention well-camouflaged, are for obvious reasons difficult to discover. In fact, in just the past few years, the number of known species has doubled to 70, reports Discover. But one recently-identified species—Phryganistria heusii yentuenis—is particularly striking: The females can reach 21 inches in length, making them the second-longest known insects on the planet after Chan’s megastick, which was found on the island of Borneo in 2008.
Stick insects are unique in several ways. For one, they not only look strikingly like twigs, but they can even change color in an attempt to hide. They also engage in ultra-lengthy mating sessions, sometimes clinging to one another for months at a time. And at least in this new species, the females tend to be twice as long as the males. Entomologists from Belgium traveled to Vietnam to see what they could find, and happened upon these behemoths in a bush, reports Wired. Working with local biologists, the researchers say they expect the number of known species to double again in the next few years. (The world's longest insect clocks in at 22.3 inches when outstretched.)