European Stag Beetle

 EUROPEAN STAG BEETLE (Lucanus cervus)

Modified from wikipedia
Original image by Simon A. Eugster

Stag beetles are a whole group of insects with big fuck-off horns on their face. I'm gonna talk about the best-known species, Lucanus cervus, whose name means "Lucanian deer", and is sort of condescending to the literal deer that presumably live in Lucania.

Appearance

Stag beetles exhibit sexual dimorphism, which means the females look physically different from the males. Female stag beetles look pretty much like your average beetle - that is to say, pretty and shiny, but don't make you say "woah, what the hell is that thing???" The male stag beetle (pictured), on the other hand, looks absolutely ridiculous. Like, what do you have going on there, buddy? Pinchers? For pinching? Who are you going to pinch with those? What look like pinchers are actually grotesquely oversized mandibles - the part of the insect used for grabbing and breaking up food. They need really powerful mandible muscles to be able to move them at all, and because the mandibles are so long, they presumably aren't very useful for delivering food to the animal's mouth. 

But the real question on all of our minds is, "will they pinch ME? And, if so, will it hurt?" The answer is, yes, they can pinch you if you fuck with them enough, but no, it won't hurt very much. Their mandibles are not for eating, or for fighting off predators - which might make you wonder what in the world they do with them. Read on, friend, and I will tell you.

Edit: My friend Yana informs me that the females in fact do have a painful bite! So here is a little rhyme just for you - mandibles look scary? Okay to carry. Mandibles look okay? Stay the hell away!

Points: 0/1 for being ridiculous and not even good for biting people

Behaviour

The most documented behaviour of stag beetles is their sparring. Males use those big, fearsome mandibles to wrassle and flip each other off of logs. It's kind of cute. The winner of these sparring matches gets to have sex with more lady beetles (not... not actual lady beetles, but like... lady stag beetles). L. cervus, henceforth referred to in this article as Dr. Pinch, is weird among stag beetles in that their mandibles aren't actually that strong, and break if the beetles use their maximum biting power. And yet still they fight, risking crippling damage, because they're that horny. The takeaway here is that Dr. Pinch is a baller who doesn't give a shit about nothing about nothing except making sweet, sweet love.

Points: 1/1

Distribution

The name "Lucanus" points to a pretty specific region of southern Italy which technically doesn't exist anymore. I mean, the region didn't go anywhere, but it's no longer called Lucania. Dr. Pinch lives in forests throughout Western Europe, so the name is sort of misleading. Anyway. Forests are getting smaller the whole world over, so Dr. Pinch would be better off living in like... condos or something, which seem to proliferate endlessly. 

Points: 0/1

Ecology

Whether you love or hate insects, you have to respect that they're a major part of any ecosystem. They're food for tons of other animals, including crows and foxes, which I think most of us agree are cool animals. And Dr. Pinch larvae feed on dead wood - without wood-eating beetles, we'd all be ass deep in rotten wood by now. I suggest you take a minute today to thank a beetle for their service.

Points: 1/1

Evolution

Dr. Pinch is a member of the Lucanidae beetle family, most of which have big, gnarly looking mandibles. Because only the males have these whacky looking mouth parts, they're probably the result of what's called runaway sexual selection. The deal with that is this: some feature is favoured in one sex for whatever reason. Members of that sex with a pronounced feature get laid more and make more babies. But what's attractive (or otherwise advantageous) is not the feature itself, but how much it differs from other members of the same sex. So if only males with the biggest mandibles get to mate, then the resulting male babies will have really big mandibles. In the next generation, the males with the biggest mandibles get to mate and produce offspring with really, really big mandibles. Then in the next generation, the males with the biggest mandibles get to mate and so on and so on until you end up with mandibles too big to be useful for anything except... being big mandibles. 

This is a cool example that demonstrates how evolution and selection don't really have a plan, they're literally only about who gets to produce more kids. If kid-production is tied to something really stupid (like having ginormous pinchers on your face), evolution doesn't give a fuck and just rolls with it. Really makes you think.

Points: 0.5/1 for being kind of stupid but for also being kind of funny

Life History

So I've been going on about the features of the adult version of Dr. Pinch and largely ignoring its larval stage. This was wrong of me, because Dr. Pinch is one of those insects that spends the majority of its life as a grub. The grubs look like any other beetle larva - pale, fleshy, pretty gross - and hang out in the woods, just munching on logs and growing, having a time. At the end of their lives, they metamorphose into a beetle, fly around a bit, fight each other, mate, lay eggs, and get eaten by stuff. This gives me hope that though I've spent the last three decades loafing around and drinking beer, the last couple years of my life will be very action packed and exciting.

Points: 1/1

Interaction with Humans

Because Dr. Pinch lives in the woods, and because woods get used for... wood, they're experiencing population declines due to shrinking habitat. They don't really bother anybody, but fuck them for living on and in a finite resource that humans use for stuff.

They're also a popular pet in Japan, and people sometimes get them to battle each other like real life Pokemon which is both fun and a little bit sad. The ethical ramifications of Pokemon aside, they're also a problem because, like all pets, people sometimes release them into the wild either accidentally or on purpose. Japanese stag beetles have their own problems, and competition from invasive European beetles doesn't help them any. This is a problem worldwide with people keeping various insects as pets, so please, if you have a non-native pet bug that you don't want anymore, at least have the decency to squish it.

Points: 0/1

Final Score: 3.5/7
Verdict: Dr. Pinch isn't bad, it's just not as cool as I was hoping

References

• Goyens J, Dirckx J, Dierick M, Van Hoorebeck L, Aerts P. 2014. Biomechanical determinants of bite force dimorphism in Cyclommatus metallifer stag beetles. Journal of Experimental Biology. 217: 1065-1071
• Goyens J, Dirckx J, Aerts P. 2016. Jaw morphology and fighting forces in stag beetles. Journal of Experimental Biology. 219: 2955-2961
• Nieto A, Mannerkoski I, Pettersson R, Mason F, Mendez M, Schmidl J. 2010. Lucanus cervus. IUCN Redlist. [Link]