Larva Farms

With the ability to eat twice their body mass a day, Larva may be the solution to our planet’s waste. Professor David Hu is conducting research to see how the appetites of these tiny creatures can combat human waste issues.


With the ability to eat twice their body mass a day, larva may be the solution to our planet's waste.

Professor David Hu is conducting research to see how the appetites of these tiny creatures can combat human waste issues.

Here's a look.

What is the 'dog food bowl' problem?

Eating requires you to make direct contact with the food, and food of a given size has only so many slots around it.

And as soon as all those slots are filled, they can only really eat at this maximum rate.

So the size of the bowl determines how many puppies can be eating at any given time.

We basically want to determine, if you have 100, 1,000, 10,000, how do those numbers affect how quickly food is consumed?

But if you want to study this problem at that scale, you're gonna need something a little different from a puppy.

[ Upbeat, distorted music plays ]

I mean they're really just hungry little babies.

♪♪ My name is David Hu, and I study how animals move.

We use engineering and physics techniques to build models for how these animals can do these amazing tasks.

Such as eating enormous amounts of food.

The black-soldier-fly larva can eat twice their body mass in a day.

They'll eat vegetable matter, road kill.

If you're dead, they will eat you.

But if they've got other options, they'll go for other stuff, too, like pizza.

And this makes them incredibly useful.

They're raised in these fly-larva farms, where the dream of these larva farms is to bring in 100 tons of restaurant and human home-consumer waste to these vast bins and have 100 tons of food waste be eaten in an entire day, and then they can multiply, and their own bodies can be used for agriculture.

To be used as a high-protein food for chickens or farm-raised fish.

So, in growing these larva, one of the big questions is how quickly can they eat, because the whole idea is to allow them to eat as much food as possible.

And so if you have more and more larva, is food just consumed just as quickly?

Is there an actual limit to their appetite?

So, we placed these orange slices inside these bins of different larva, and we observed how quickly they could eat.

The results were consuming.

Naively, you'd expect the rate of food consumption to be proportional to the number of larva that are around it, but they happen to eat almost 10 times faster.

So this idea that each larva is just eating at a constant rate only gives a small part of the picture.

And so Dr. Hu and grad student Olga Shishkov began looking at the behavior of individual larva.

First thing we noticed is that the larva only ate for small fractions of an hour.

Most of the time, three fourths of an hour, a larva that's around a piece of food is just blocking the other larva.

They would ordinarily take up a spot and slow down the rate of food consumption.

So it wasn't their individual appetites that enabled them to consume massive quantities of food.

Undeterred, the researchers decided to approach their problem as only mechanical engineers could.

If you want to measure the pressure in a room, you don't trap every single molecule in a room.

What you do is come up with rules for how groups of these molecules would behave under certain conditions.

With this perspective, you can start to see the maggots' motion in a new light.

Even though they're alive, we can really treat them as sort of non-living things that follow these really simple rules.

Without any food, they simply just follow each other and slosh back and forth, but as soon as you put small food scraps into the larvae, they start generating these tiny vortices, whirlpools.

The food causes a chain reaction.

Individual larvae can be activated by the motion of their neighbors.

And if a single larva takes a bite of food, it is super activated, and it continues to swarm around and look for food.

And they actively move throughout these blockades, these larvae that are sitting around and not eating.

And that helps other larvae get to the food, kind of like a buffet line.

People are sort of pushing them out of the way just so each of them grabs one bite.

You can imagine the buffet line would be eaten much faster.

Now that the researchers have discovered the larvae's solution to the dog food bowl problem, their next step is to see if they can create a mathematical model for all this maggoty emotion.

You can see the larvae as kind of like a -- like waves in an ocean.

They're sloshing back and forth, and here they're generating their own sloshing forces.

So, how could we actually measure the forces of them sloshing?

And so what we did was we put them in a device, kind of like a vise, where we sort of measure the forces they push up against the walls.

And we find that as soon as you put in food, they really activate and they really push against the walls.

And then the pushing sort of decreases and decreases as the food goes away.

Believe it or not, Dr. Hu's aim is not to create more and more fodder for your nightmares.

Yeah, after we die, this is what's gonna happen to us -- these larvae.

But they can -- [ Laughs ] They can provide a lot of use before we're gone.

It's the one thing that doesn't have any human diseases and that will get rid of all our food waste.

That is -- 1/3 of the food that goes into our restaurants and our homes is actually thrown in the trash.

Much of which ends up as water-polluting sludge oozing out of a landfill.

You just got to get on eye level with the larvae and see what they're trying to do.

You can admire how much they really want to eat.

I think they're pretty cute.

Okay, fine, they do give me nightmares.

For 'Science Friday,' I'm Luke Groskin.