The newly described stick insect Phryganistria heusii yentuensis is over a foot long (32cm), or 21 inches (54 cm) with its front legs stretched out. It's the second biggest living insect that has been described. Ever.

Walking sticks are a group of leaf-eating insects that look like ... well, sticks and twigs. They are not easy animals to study. Researchers from the Royal Belgian Institute of Natural Sciences (RBINS) captured the new species in Vietnam.

Catching and observing walking sticks is especially difficult because they are mostly active at night. And by "active," please understand I mean lumbering along slowly while pretending to be branches swaying in the breeze.

Male and female *Phryganistria heusii yentueensis *having sex. Note how small the male is compared to the female. Bresseel & Constant, RBINS

The new walking stick species were found using a classic entomological technique: beating. It involves a really large stick and a bed sheet. You put the sheet on the ground and whack a bush with your stick. Many insects release their grip and play dead when disturbed, and so drop onto your sheet for easy retrieval.

Alas, the researchers haven't responded to my inquiry about what words they said (or at what volume) when these huge insects flopped out of the undergrowth. I suspect some rather strong language was used.

CORRECTION 12/8/2014: I did finally hear back from the researchers! They declined to elaborate on what, exactly, words were spoken upon finding this insect, but they did confirm the use of strong language. They also clarified that while beating was used for some other species discovered in the research paper, this giant species was spotted in a bush. So, I was not correct to say that beating was the methodology for this particular species.

It's Harder to Tell Sticks Apart Than You Think

Stick insects have sexual dimorphism, a fancy way of saying males and females differ remarkably in size and color. It's not uncommon for female stick insects to be twice the size of males.

The research wasn't just collecting new insects; old preserved specimens were also examined. Museum specimens (and their confusing, hand-written labels from 100 years ago in a variety of languages) housed in Russia, China, the US, and other spots around the globe were examined.

Because the sexes vary so much, and there are lots of big sticky things in Asian forests, early collectors tended to decide each new big bug they found was a new species. This current research tried to figure out which specimens actually belonged to the same species.

Bresseel & Constant, RBINS

Oh, Also? Stick Insects are Tantric Sex Masters

One of the newly described species was observed mating in captivity. Male Phryganistria bachmaensis remain attached to females for two days. That's not unusual – some researchers have found stick insects hooking up for over a month. One example:

*“Indian stick insect Necroscia sparaxes may remain coupled for up to 79 days”… Intromission may occur only initially or intermittently....

*In captivity, Diapheromera veliei and D. covilleae pair for 3 to 136 hours and the penis may be inserted and removed up to 9 times."

Being stuck together for days seems like a not smart thing to do, if you're a large and tasty insect. Or, in this case, two large plant-eating insects belonging to a group that specializes in being invisible to predators by looking like a stick. Two sticks having sex is the sort of thing I’d notice, anyway.

It’s generally thought that the male hangs around in order to have repeated matings, but also to drive off other males that hope to get lucky. I found several reports of stick insect Ménage à trois in the literature, including this [etching of kinky stick insect activity](http://membracid.files.wordpress.com/2012/07/insectthreesome.png "FYI: "Would you like to see my insect etchings" is not a useful pickup-line"). The male is – literally – cock-blocking a competitor.

__ A Sticky Situation__

Vietnam is part of the Indo-Burma Biodiversity Hotspot, a region of Asia rich with plants and animals that are found nowhere else on Earth. It's also an area with dense human population centers. The European Union and the International Union for Conservation of Nature, among other organizations, are issuing grants to fund cooperative research enterprises like the one that led to the discovery of these new insect species.

The authors on this new paper are working in cooperation with Vietnamese biologists to help build a reference museum collection, and develop keys to identify local Vietnamese insects. It's expected the team will double the described species of stick insects from the region over the next few years.

I can't wait to see what other treasures are documented in the forests and marshes of Vietnam – and I hope that scientists will be studying them for decades to come.

Video of the new insects in captivity (Dutch Language)

Bresseel J. & Constant J. 2014. Giant Sticks from Vietnam and China, with three new taxa including the second longest insect known to date (Phasmatodea, Phasmatidae, Clitumninae, Pharnaciini). European Journal of Taxonomy 104: 1–38. http://dx.doi.org/10.5852/ejt.2014.104