“Ionic liquids: When all the little ants go chemical-warfaring.”

An ionic liquid is a salt that’s in the liquid state. But let’s define “salt”, because in this context, it’s not just for shakers and hot buttered popcorn.

Chemically, a salt is any mixture of positively-charged ions (called “cations”) and negatively-charged ions (aka “anions”). Salts form when an acid (which contains positive ions) and a base (chock full of negative ions) mix and neutralize each other. The best-known salt is made of sodium cations and chloride anions, and it’s so common it gets the saltiest name possible: “salt”. Or “table salt”. Or “that stuff the chef forgot to put on the bean salad, and that’s why the dude got Chopped”.

Any salt can be an ionic liquid, under the right conditions — even sodium chloride. You just have to heat it to fifteen hundred degrees or so Fahrenheit.

And then pay twelve bucks at some upscale Euro-gastro-bistro to have it ladled over your artisinal free-range pommes frites, probably. Which just goes to show, you don’t really want an ionic liquid made of table salt.

Some ionic liquids are more useful, however. Most are poor electrical conductors, highly viscous and some are even liquid at room temperature. These tend to have names like 1-alkyl-3-methylimidazolium tetrafluoroborate, which is somewhat harder to pronounce than “salt”.

It’s also harder to pronounce than the name of that Kyrgyzstani guy who plays on your favorite hockey team. Barely.

What are ionic liquids good for? Lots of stuff! Industries like cellulose processing, industrial gas storage, nuclear fuel reprocessing and waste recycling use (or are researching) ionic liquids. They’re also being tested as electrolytes in batteries, treating wounds infected with bacterial biofilms and for heat transfer in solar energy systems. All of these things are pretty important — and also kind of boring, unless you’re a chemist or a drug-resistant biofilm.

So let’s talk about ants instead.

All the ionic liquids mentioned above are artificial, created in the laboratory. In fact, not a single naturally-occurring ionic liquid had ever been observed — until scientists took a closer look at ants.

But not with a magnifying glass on a sunny day, because that’s cruel.

South American fire ants invaded the U.S. several years ago, and it’s known that their “fire” comes from a vicious burny venom made of toxic alkaloids, which are bases. They’ve recently been joined by another South American ant species called tawny crazy ants — not to be confused with Tawny crazy Kitaen, which is a whoooole other sort of ecological hazard.

These ants have been fighting over territory for ages, and the tawny ants are one of very few species that can survive the fire ant’s flesh-melting juice. Scientists only recently discovered how they do it — by secreting and coating themselves with formic acid. The acid mixes with the fire ants’ alkaloids, neutralizing it to produce a harmless ionic liquid.

With chemical defenses in place, the tawny crazy ants survive the fire ants’ onslaught 98% of the time. And they do it with the only ionic liquid known (so far) in nature. That’s one “salt of the earth” species, there.