Termites. Just the name alone often brings feelings of revulsion, as few people can love a major pest or creepy crawly. Termites exist on every continent except Antarctica, and globally probably number in the trillions. Now, each termite is very small, but when you have that many, they will need a great deal of food to sustain themselves. Termites primarily eat cellulose, which is the tough fibrous stuff that makes up plant stems. This is why termites can wreak havoc on homes, as they will eat away at the wooden framing.
Before we get into about why termites might actually be useful, let's talk a little more about them.
Contrary to popular belief, termites are not ants, even though they rather look like them. Termites are sometimes referred to as white ants, but don't let that fool you. In fact, it is likely that ants would be highly insulted to be confused with termites, as the two types of insects commonly go to war with each other. The truth behind termites is much more sinister. Many many years ago, during the Triassic period, there were some species of social, wood eating cockroaches. Over the eons they changed and evolved, and today we call them termites, but they are really just a highly specialized type of cockroach. Some of the more primitive species of termite have a striking resemblance to cockroaches, a leftover from their ancient brethren.
Termites primarily eat cellulose, but like all animals they cannot digest it efficiently. For that, termites have certain protozoa living in their guts that help break down the fibers. In turn, these protozoa have certain bacteria living in them that contribute valuable enzymes. This relationship evolved millions of years ago with the original cockroaches, and has been handed down. Since all the parties involved would die unless they are all together, you could almost say that the termite is a composite organism.
Returning to our original question: what are termites good for? They are major pests and gleefully eat crops and homes. Why on earth would we want to cultivate them? The answer lies in a byproduct of their complex digestion.
Termites, when they break down cellulose, produce huge amounts of methane and hydrogen. Methane is the same stuff as natural gas, and hydrogen has many important uses as well. Currently, North America has a glut of geologic methane and won't need the termites, but North America is not the world. High gas prices in Europe and Asia have led some to consider alternative sources for the stuff.
Humanity produces and throws away billions of tons of paper per year, which is a lot. Now, a piece of junk mail sitting in your garbage can is not terribly valuable. However, methane gas is, as it can be used for heating, electricity, and feedstock for chemicals. Therefore, if you could turn your junk mail into methane instead of throwing it away, you turn garbage into something useful.
That's where the termites come in. If we could breed and cultivate them on large farms, we could feed them our excess paper and make them turn it into gas for us. Instead of paper becoming trash that must be thrown away, it would become a valuable feedstock for gas production. The termites would happily eat our junk mail, and we would extract the gas they produce for our own purposes. Both species, man and termite, would come out ahead.
Obviously, there are difficulties with this process. No one has ever tried raising termites on an industrial scale before, probably because no one ever wanted to. The farm would also have to be made out of metal and plastic, or concrete, to prevent the termites from eating their way out. In addition, the cages would have to be airtight so that the gas could be extracted, with air piped in as needed. Finally, there are undoubtedly legal concerns about housing 100 billion termites in a facility. If they escape, they would seriously interfere with the local ecosystem.
Before you go out and start cultivating your own termite farm for experiments, I would highly recommend doing it away from your home.