Welcome to a new ongoing series on the bearers of nature’s most fascinating anuses. Today we’re going to talk about Stenus Rove Beetles.

Aliases: The Nominator. Steven.

Known for: Wing origami. Long range nom snatching. Zipping across water at absurd speeds. Chemical warfare.

Likes: Springtails! Tastier springtails. Other small things that may be tasty. Jet propulsion.

Dislikes: Spiders. Bigger beetles. Frogs. Michael Bay movies.

Favorite Quote: “If one could conclude as to the nature of the Creator from a study of creation, it would appear that God has an inordinate fondness for stars and beetles.” - J.B.S. Haldane


I’d like to introduce you to Steven. Steven may not look much like a beetle to you, but he’d likely argue that you didn’t look much like a mammal.


Steven is a rove beetle, a family of beetles that chose the Donald Duck route and spend their lives going bottomless. Other beetles may make fun of Steven and his kind, but Steven doesn’t care. Steven has some amazing tricks they don’t. Also: Steven has a really tiny brain so it’s pretty hard to hurt his feelings.

What’s special about Steven?

Let’s work our way from head to butt, shall we?


Much like larval dragonflies and xenomorphs, Steven has a trick up his mouthparts.

Steven’s tiny, but if you’re smaller than he’s absolutely freaking terrifying. He can fire his little mouth-spear almost half the length of his body.


Needless to say, he uses it a lot. Wouldn’t you if you could? You’d never need to ask ‘please pass the chicken’.

Not that rove beetles are known for their politeness.

Working our way back, we have his wings. Yes, Steven can fly... he’s not an amazing flier, but he can get around when he needs to.


But where ARE his wings? Well, just like most other beetles they’re under his elytra (back-shell-thing), which I’m sure you’ll notice are really teensey.

So does Steven have tiny little fairy wings? Does he flap them really, really fast?


Of course not, that’d be silly. Instead Steven is a master of origami.

Look at one of Steve’s relatives go!

And so our journey down Steven’s limber form has come to a middle.

Let’s talk about Steven’s amazing anus. That butt’s not just for folding wings after all!


Rove beetles happen to be master chemists. Their ability to manufacture interesting compounds is well known...but we’ll skip by your typical chemical defenses and lures and just zero in on Steven’s coolest excretion.

Steven can walk on water...which is pretty awesome, but it’s hard to run very fast on water. There’s not much to grip and at his size he’s subject to all kinds of forces that we gigantic humans can cheerfully ignore.


So when Steven really needs to get away quickly, it’s not his legs that do all the work, it’s his anus. That, and a little chemical creatively named stenusin.

Stenusin is VERY hydrophobic, and the end result is much like what happens if you drop a bit of dishsoap into a bowl of water...everything rushes to the edges. For Steven it’s QUITE the rush. He can meander about on the surface of the water at maybe 2-3 cm/second, when he turns on his anal-oil-jet-engine he suddenly accelerates to 45-70 cm/second.


That’s like you suddenly accelerating to over 400mph in the blink of an eye. It’s called Marangoni Propulsion, and Steven is a master of it.

You’d die, of course...those G forces are absurd...but for Steven it’s just another day hanging out by the pond.


Sure, he still may be just a bug...but he has a spectacular butt.

Credits: top image of Steven: Pavel Krasensky

Steven’s lovely mouth: Bogleech by way of Scrubmuncher

About your host.