That lump on the side of this tree in the Amazon?

It's packed with termites.

In the rainforest, that's a good thing.

They break down wood into stuff other creatures can eat.

But inside our homes, termites are pests.

They cost us billions of dollars of damage every year.

Take these dampwood termites that live on the cool California coast.

They eat wood that's wet or decayed, maybe from a leak in your house.

Slowly, but surely, they gnaw and scrape away.

What comes out the other end isn't waste.

It serves as a kind of mortar.

And dried poop pellets make perfect building blocks for their nests.

In other words, they're turning your house into theirs.

What's amazing is that they can digest wood, which is so hard, and get nutrients out of it.

We certainly can't do that.

Termites are one of the only animals that can.

It turns out they don't do this alone.

Researchers are looking inside termites to figure out who's actually responsible for this feat.

At the Exploratorium, in San Francisco, museum biologists give the insect a little puff of carbon dioxide.

When it's nice and relaxed, the termite poops itself.

Under the microscope, multitudes appear.

Hundreds of species of microbes live packed inside a termite's gut, about one one-thousandth of a teaspoon.

This big one is called Trichonympha.

It's not an animal, plant or fungus.

It's a protist.

Watch it move with the help of its flagella.

Protists like Trichonympha are essential for termites to turn the wood into a source of energy.

They do this by fermenting the wood, much the same way a brewer turns grain into beer.

Something else is hidden deep in the termite's gut: a powerful bacterium that combines nitrogen from the air and calories from the wood to make protein.

That's like turning a potato into a steak.

Termites can't live without their microbes.

And many of these microbes can't live outside the termite.

So what if we used the microbes against their hosts?

Right now, when we want to get rid of termites, we fumigate our houses with poison.

But maybe we could just kill the protists instead.

Louisiana State University entomologists are engineering a gut bacterium to kill gut protists.

They'd sneak the bacteria into the termite colony on something the termites would eat.

The bacteria would kill the protists that help the termites digest wood, leaving them surrounded by food but starving.