Bee Stinger Anatomy: An evolved machine

This is what the end of a honey bee stinger looks like under an electron microscope. Notice those wicked backward-facing barbs.

Here’s an animated diagram of the entire stinger—muscles, venom sac, venom pumps, and all. When you look at this, you might be thinking, “No way, that’s fake. Surely a bee stinger isn’t this complex, right?”

Today, we’ll compare this diagram to actual footage of honey bee stingers, footage like this right here, and we’ll look at several high-resolution images taken with electron microscopes.

Stated Clearly presents: How Do Bee Stingers Work?

Bees are very gentle little critters. Even though they can sting, they usually only do so if you attack them first, if you accidentally smash one, or if they think you’re trying to attack their hive. That said, when bees do sting, it hurts a lot. Notice that even after the stinger is detached, zombie-like muscles keep digging and injecting venom.

The power of this tiny weapon comes not just from its potent venom—venom that can destroy human cells—but also from the stinger’s surprisingly complex structure.

Let’s start out our tour by zooming in on the point of the spear. The end of a honey bee stinger is made of three parts: a stabilizing rod, technically called a stylet, and two digging blades called lancets. Each lancet is equipped with backward-facing barbs.

Let’s animate this image for you. Those lancets slide on the stylet, their movements powered by the muscles left behind when a bee releases its stinger. The blades move back and forth in a saw-like motion. When a stinger enters your skin, each time a blade tugs upward, those backward-facing barbs catch in your skin, pulling the rest of the stinger deeper into your flesh. Alternating movements of each lancet allow the stinger to essentially “walk” further and further into your skin with each step of the lancet.

Zooming out, we see that the stylet, or stabilizing rod, broadens to form a large, rigid venom bulb. If we peer through its surface, we see that attached to the shaft of each digging blade, each lancet, is a pump valve that fits inside that venom bulb. Surrounding the bulb are muscles attached to plates of exoskeleton that power each lancet shaft. Every muscle pull simultaneously moves the lancet’s digging blade and its pump valve, automatically injecting more venom every time it digs. It’s a two-for-one deal.

In this footage, we’re looking at the stinger from a side view. Even though it’s hard to see clearly through the bulb, the bulb is the dark section near the skin. The pump valves are visible—you see that.

Sitting on top of it all is a large venom sac and several glands that originally produced the venom in that sac.

At this point, you might be wondering: if the shaft of the stinger is made of three parts—a stylet and two moving lancets—what stops the venom from leaking out at the seams? Shouldn’t it spill out everywhere? How does venom only exit at the end of the stinger?

This is a cross-section of the stinger as seen through an electron microscope. On the top are the lancet shafts; on the bottom is the stylet, or what I’ve been calling the stabilizing rod. Check this out—each lancet moves along a runner, also called a ragus or rachis, coming out of the stylet. It’s a classic tongue-and-groove system, and that joint is tightly sealed shut.

Here’s what those runners look like if the lancets are removed. Furthermore, each lancet shaft has a curled, flexible latch connecting it to its companion. The latch on the right was damaged when this cross-section was made. I’ll fix that here with some Photoshop magic.

Altogether, these structures form a watertight hypodermic needle, allowing venom to flow through the inner canal without leaking at any of the joints.

Here we’re looking at a honey bee stinger from a slight side angle, again under an electron microscope. I’ll color this black-and-white image to match our diagram.

Here in green, we see the venom bulb. It’s partly hidden by the structures surrounding it, so there’s a dotted line to show what parts are hidden. Up at the top, we have the venom sac. Underneath that are the lancet shafts in blue.

If we zoom out, we can contrast the diagram I’ve made with the real thing. The stinger of a honey bee—it’s one of the most amazing weapons in nature. I would rank it above snake fangs, which are also amazing, and I’d put it at least on par with the chameleon’s tongue.

Sadly, though, the honey bee stinger is far from perfect. The wound left behind in a bee’s body after she stings will usually kill her. Her life is the price she pays to defend her hive. Only the female bees have stingers; male bees cannot sting. We’ll learn exactly why that is in an upcoming video, Evidence for Evolution in Your Own Backyard. That one is going to be good—make sure you’re subscribed and hit the bell icon if you don’t want to miss it.

For now, though, let’s take a moment to stop and appreciate what a fantastic contraption the stinger is. From a bee’s perspective, you are Godzilla. In those films, Godzilla is impervious to our greatest weapons. Yet the amount of pain a single bee can deliver with just one sting—unless you’re used to it—is usually enough to ruin a person’s day.

On top of that, if you happen to be extremely allergic—which is super rare, mind you—a single sting can kill you. That is impressive.

Normally, I try not to brag, but I have to say I’m proud of the diagram I’ve been showing you. It’s currently the most accurate animated stinger diagram on the internet. This is an updated version of the one I published back in 2014. Someday, I’ll do a third update to show how all the articulations and individual muscles work, but this current update highlights how the pump valves slide past and replace each other when in use.

This ability was first described in 1910 by entomologist R. E. Snodgrass. I dedicate this diagram to him.

This new version also highlights a structure that, to my knowledge, has never been described before. Right here is a joint called the basal articulation, which has been officially described. If we look at the stinger from a side view, we can see how it works. This joint lets the stinger swing forward and backward. This joint is found in the ovipositors and stingers of many types of ants, bees, and wasps.

But in some species, honey bees included, the bases of the condyles in this joint seem to have taken on a second function. They appear to act as a zipper head or girdle, which zips the lancet shafts together down the midline as they pass through that girdle. It’s a really neat mechanism.

Bees are not the only ones that seem to have this girdle. Here’s the same thing in the stinger of a digger wasp. I’m currently in conversations with several researchers to see if this girdle function has ever been described before in the scientific literature. If not—and if the girdle actually works the way I think it does—it should be officially described. It’s a beautiful example of what Stephen J. Gould called an exaptation. Evolution often generates new functional structures by simply modifying or expanding old structures.

If you found this diagram and video helpful, I’d love your support on future projects over on Patreon. Those who support my work get to see videos early, gain access to high-resolution images for printing, and—if you or someone you know is a teacher—patrons also get PowerPoint slides for these animations, which they can use in their own classrooms or give to a teacher. The slides for this video, of course, include the fully animated version of this diagram.

I’m Jon Perry, signing out. You’ve just watched How Do Bee Stingers Work? Stated Clearly.