Sunday, 22 November 2015

Spider Wasp

Image: Eframgoldberg
If you're an arachnophobe, you might like to think of this as "the enemy of my enemy is my friend". Unless you also hate wasps. If you suffer from spheksophobia be aware that many Spider Wasps are scarier than your average wasp and the enemy of your enemy is a super-powerful enemy.

You can't hope to get away from them either, unless you enjoy the crisp, windswept delights of Antarctica. There are some 5,000 species of Spider Wasp making up the Pompilidae family and they're found wherever there are spiders. And that's everywhere. Except the frozen, wind-beaten deathlands of Antarctica.

Let's take a look at the very first Spider Wasp to earn a scientific name, the one that lent its name to the whole Pompilidae family.

Image: Martin Grimm
Pompilus cinereus, a Pompilin
It's Pompilus cinereus, the Leaden Spider Wasp. This species has a vast distribution, being found from Britain to Madagascar and Japan to Australia. However, it reaches a length of less than 1 cm (0.5 in) so it's a bit of tiddler as Spider Wasps go.

But why is a Spider Wasp called a Spider Wasp? What exactly is so "Spider" about them?

Well, let's begin with a female Leaden Spider Wasp. She's got an egg to lay and this is the day. This is Lay Day. But she has no time to celebrate. Spider Wasps are solitary so she won't be having any Lay Day parties with her friends. She just wakes up in the morning, spends a bit of time grooming so she's fresh and presentable and flies off to a flower for some breakfast.

Image: cotinis
Entypus unifasciatus, a Pepsin
Her meal will consist of sweet tasty nectar. Spider Wasps love nectar because it gives them lots of sugary energy to tackle the day's tasks. There's a lot of work to be done on Lay Day and our Spider Wasp is not some queen bee with an army of servants to help. It's all down to her. And so, armed with a pleasant sugar rush, she sets out spider-hunting. Could've done with a nice blunderbuss or maybe a big shoe, perhaps an upside down glass and a piece of paper if she wanted to be humane, but no, just sugar.

Besides, she doesn't want to be humane.

Leaden Spider Wasps are particularly fond of Wolf Spiders, who happen to be rather tough, agile hunters who take down prey with speed and venom, not webs. Our Spider Wasp shows no fear. She is very active, not to say hyperactive, as she wanders around with herky-jerky movements, antennae twitching manically with every step.

Image: Eric Isley
Tachypompilus ferrugineus, a Pepsin, with a Wolf Spider
Eventually she finds a nice, big Wolf Spider. A struggle begins. It can appear to be of the EPIC variety. Two mighty warriors clashing, the wasp like some lithe and nimble elf, the spider a huge, ferocious orc. Then again, the Spider Wasp is pretty darn good at hunting spiders. She searches for openings and opportunities. She swiftly leaps out of reach of the spider's lunging attacks. She uses her long legs to grapple, keeping out of the way of the spider's fangs. Finally, she stings the spider and the job is done. Expertly.

With that unpleasantness over the Spider Wasp is left with the prize of a live, paralysed spider about the same size as herself or larger. It would have been nice to get that as a Lay Day present from her friends or parents or something but no, this is not a world where people put little bows on paralysed spiders and give them as gifts. That would just be weird.

As it is, our Spider Wasp may well choose to bury her spider in sandy soil nearby, just to make sure it doesn't get stolen. And there will be sandy soil nearby because Leaden Spider Wasps need it and they don't stray far from it.

Video: Eric Eaton

Now the real excavation work begins. She finds a promising site and sets about digging a small nest out of that sandy soil she likes so much. Then she digs up her spider, carries it to the nest and deposits it within. She lays a single egg to go with the single spider, then she leaves the nest, covers the entrance with soil and finally leaves entirely to do it all over again for another egg. Maybe she'll stop by a flower first.

Something rather horrible happens within a few hours. The spider partially comes out of paralysis. The poor fellow seems out of sorts, which is understandable, and he just wanders around within the nest leaving silk all over the place. This actually improves the structural integrity of the nest. I don't know if that was his intention, but he may be too far gone to have intentions at this point.

Within a few days the egg hatches and a Spider Wasp grub merrily consumes the spider, killing it. Horribly. So at least someone got a spider from their parents for Lay Day. And, naturally enough, that spider gives all the nourishment a grub needs to grow, pupate and emerge as an adult, nectar-supping Spider Wasp.

Image: Alain C.
This life history is a good template for most Spider Wasps, though there are numerous differences and details among species, genera and subfamilies. If we just stay within Pompilinae, the subfamily that the Leaden Spider Wasp belongs to, we find several different ways of doing things.

For example, some Spider Wasps don't like to dig into soil. They prefer crevices among rocks or tree bark. Some go the extra mile and construct mud nests. Others go the opposite way. They sting a spider to paralyse it for a while but then they simply drop an egg on it and leave. The spider wakes up and goes about its business pretty much as normal until the egg hatches and the grub eats it alive. Also horrible.

Then there's the actual target. Some Spider Wasps will only hunt a single species of spider, others can choose from a whole family, still others have an even wider choice. The Leaden Spider Wasp really likes the Wolf Spider family, though she'll also target other, similar spiders.

Some Spider Wasps prefer orb-weavers and they bear special scales on their feet that allow them to walk on webs and safely stalk their prey. There's even one Spider Wasp that goes after Fishing Spiders. These are spiders that walk on water so the Spider Wasp has to paralyse it and then itself walk on water, dragging the corpse behind it to get back to land. It's the most morbid miracle, ever!

And yet, and yet, and yet... even all that is just Pompilinae, one of four subfamilies.

Image: David Crummey
If you're scared of wasps then the real super-powerful super-enemies are in the subfamily Pepsinae. This group includes the Tarantula Hawks, which are gigantic wasps some of whom reach over 5 cm (2 in). They hunt suitably enormous spiders, like big, hairy tarantulas.

Some of them... perhaps after drinking too much nectar... will even attempt to tackle the aggressive, horrifically venomous Brazilian Wandering Spider. They can usually win, too, because Spider Wasps are just that good at spidering.

Presumably it's no coincidence that they also happen to have one of the most excruciatingly painful stings in the world. That's pretty bad, but at least we're not the ones who get paralysed and fed to a grub in a dark hole in the ground.

Then there're the genus Auplopus. They have a kind of "evil gangster" method for solving a certain problem. You know how the Leaden Spider Wasps's spider woke up and wandered around in the nest? Auplopus Spider Wasps don't like that. They don't like that at all. And they don't negotiate, either...

Image: Lynette
They just chew the spider's legs off. That'll be another "horrible", then.

The next subfamily is Ctenocerinae. It's quite small and contains a host of species that are a lot like the Pepsins but specialise in hunting trapdoor spiders. There's not much information about them but they probably just sniff them out with their antennae and boldly enter the trapdoor's erstwhile hidden lair.

Image: tom murray
Ceropales maculata, a Ceropalin
Finally, Ceropalinae. This subfamily contains just two genera and has by far the fewest number of species. Those species also happen to be quite different from the other Spider Wasps. They like spiders, they just don't much care for going to the trouble of actually hunting for them.

They are what is known as kleptoparasitic, or "parasitic by theft." They don't search for spiders, they search for fellow Spider Wasps who are carrying spiders. Now you may think they'd have to be mad, crazy, kleptomaniacs to want to go messing with some of these massive Spider Wasps but somehow they just get in there, drop an egg on the spider and run.

Image: Phillip Harpootlian
The other Spider Wasp thinks the coast is clear now that she's seen off that highwaywoman, so she resumes her journey back to the nest. She lays her egg as normal, covers it all up so it's safe and sound, and leaves. Unfortunately the Ceropalin egg goes right along with it and hatches first. The grub eats the other egg and the spider and the dastardly plan is complete.

Spider Wasps are just so... so... SPIDER WASP they simply can't keep it in. Their cup of horror overfloweth and can't help but spill all over the nearest Spider Wasp.

Really, they're layer upon layer of horror. However, if you are indeed scared of both spiders and wasps, then the enemy of your enemy who is a super-powerful enemy may itself have an enemy who is also an enemy but is, hopefully, a less daunting one. Assuming you can make any sense of that, I hope it gives you some comfort.


Esther said...

Brb moving to Antartica.

I think I prefer the spiders, to be honest. At least they don't fly!

Joseph Jameson-Gould said...

Ha! Yeah, powered flight is definitely a game-changer

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