At the World’s Biggest Bug Farm, 10 Billion Maggots Recycle Food Waste

The Washington Post

12:17 JST, August 30, 2025

NESLE, France – On the world’s biggest bug farm, roughly 10 billion maggots squirm toward the day they’ll be crushed, dried and sold as an alternative form of protein powder.

None of these insects will find their way into your smoothie. They’re marketed as a more sustainable ingredient for fish feed, livestock feed and pet food. Along the way, they are tasked with eating food waste – helping to address a source responsible for a tenth of human-induced global greenhouse emissions.

In nature, black soldier fly larvae are gifted recyclers, gorging themselves on dead and decaying plants and animals, neutralizing germs and turning rot into a source of protein that nourishes fish, birds and other creatures.

The French start-up Innovafeed wants the fly larvae to do the same for human society on an industrial scale, clearing out thousands of tons of food waste and turning it into animal feed on ultraefficient, mechanized farms.

The bug farm could serve as a model for a future industry that blends eons of insect evolution with high-tech robot monitoring to help lower carbon emissions and limit the environmental damage from our food system.

But eight years after rearing its first flies, Innovafeed has yet to make a profit, and some of its most prominent competitors have filed for bankruptcy. The industry’s future depends on finding buyers willing to pay a premium for a more sustainable source of protein – and winning over regulators, who have been slow to legalize feeding insects to fish and animals.

A bug’s life begins

The bugs begin their lives in massive hatcheries, where millions of adult flies meet to mate, lay eggs and, after a 12-day orgy, die.

Small insect farms are fairly common in Asia, Africa and Latin America. But the bug farm in France is next level.

The original hatchery, set up in a greenhouse, holds 60 million flies – nearly the human population of France, the bug farmers point out. A second indoor hatchery holds 300 million, closer to the human population of the United States.

The adults do not eat, fueling their lovemaking frenzy with only the fat and protein they stored as larvae. When they find a mate, they link their bodies in the air and then descend in a graceful spiral to the floor, where they lie in amorous repose for about 20 minutes.

Two days later, the female fly will lay 500 to 1,000 tiny white eggs on a grooved wooden board.

After 12 days, most of the flies have used up their fat reserves, and their corpses blanket the floor. Any survivors fall victim to a fly trap – an industrial version of the one you might have in your home – that lures survivors with bright lights and zaps them. Then human handlers enter for the first time to collect the eggs, sweep out the dead flies and bring in a new batch of breeding adults.

Writhing and thriving

In the biggest area of the bug farm, a machine sprinkles insect eggs into plastic trays along with all the food they’ll need to fuel the first stage of their growth as larvae.

Black soldier fly larvae feed on dead animals, decaying plants and feces in the wild. Because they have such a rancid diet, they’ve developed broad immunity to diseases, producing proteins called peptides that fight harmful microbes and encourage the growth of helpful ones.

“What makes the black soldier fly the crown jewel is that it can eat anything,” said Jeff Tomberlin, a Texas A&M University entomology professor who heads the National Science Foundation Center for Insect Biomanufacturing and Innovation.

Here in Nesle, the bugs eat porridge – a combination of wheat bran and a soupy slurry called stillage produced as by-products from a neighboring grain processing factory that makes starch, sugar and ethanol. A pipeline pumps tons of bran and stillage from the wheat plant to the bug farm every day.

The only other thing the larvae need to thrive is heat and humidity, which the bug farm gets in the form of excess heat from a neighboring power plant. Another pipeline brings warm water and steam from the power plant into the bug farm, keeping the inside at a toasty 86 degrees and 70 to 80 percent humidity to imitate the bugs’ native tropical habitat.

Fueling the bugs’ growth with waste from neighboring factories is crucial for lowering the farm’s greenhouse gas emissions and making insects a sustainable source of protein. If Innovafeed trucked in fresh food from far away and burned gas to make heat, it would lose its environmental advantage.

“It’s not a given that insect protein will have a lower carbon footprint than soy protein or fish meal,” said Clément Ray, Innovafeed’s CEO. “It completely depends on the way you farm, where you get your energy from and how you feed the insects.”

The feeding is done not by humans but by robots. Machines fill plastic trays with eggs and food and stack them up in windowless storage rooms, where the bugs will hatch and eat for the first six days of their lives. Then, the robots perform a wellness check: They collect the trays, pass them through machines that use cameras and AI to count how many bugs have survived, and refill the trays with more food for the larvae’s final growth spurt.

After eight more days of bulking up in complete darkness, the bugs will have grown 10,000 times bigger than they were when they hatched.

The robots return to collect their trays. This time, they dump the trays into a sieve that separates the bugs from their poop, which has been piling up since they were born. The feces go down one conveyor belt, and the bugs go down another.

The metamorphosis

For most of the bugs, this is the end of the line. Innovafeed picks 5 percent of the larvae to go to the egg hatcheries, where they’ll be allowed to become flies and to mate, lay eggs and keep the farm going.

But the rest of the larvae are swiftly killed with hot steam, their bodies blended and separated into fats and solids. The solids are dried into protein powder, which feeds farmed fish. The fats are rendered into oil, which is sold as a dietary supplement for farm animals such as pigs or as an ingredient in pet food for dogs and cats. (The oil naturally boosts pets’ oral hygiene and gut health, according to Innovafeed.) The bugs’ feces becomes fertilizer for farms.

Insect protein is more expensive than standard feed ingredients like soybeans or forage fish – a catchall term for herring, anchovies, sardines and other wild sea creatures harvested to feed to higher-value farmed fish like salmon and trout. But bugs reared on waste can come with fewer environmental drawbacks than forage fish or soy grown in deforested regions like the Amazon.

“If we do not find new ingredients, the oceans will be overfished and depleted,” said Katherine Bryar, global marketing director for the fish feed supplier BioMar. “For the survival of the aquaculture industry, the biggest challenge is feed.”

Starting in the ’90s, BioMar started replacing the wild fish in its fish feed with soy protein to avoid overfishing, Bryar said. But later, the company realized soy came with a higher carbon footprint. “While we solved one problem, we caused another,” she said.

That’s why BioMar is buying insect protein in small quantities and studying how it could add it to fish feed. It’s also researching whether insect protein has health benefits that would justify its higher cost. Bug farmers point out that black soldier flies naturally produce antimicrobial proteins that can ward off disease and save fish or livestock farmers money on antibiotics.

“Insect protein is not just a protein,” said Nick Rousseau, who heads the U.K Edible Insect Association, a trade group for bug farmers. “Insects have their own antimicrobial peptides, which means they are like little walking antibiotics.”

But it’s a tough sell. The insect protein industry is tiny, and changing the recipes for pet food, animal feed and fish feed to use a new ingredient requires expensive and time-consuming research from companies like BioMar. In the meantime, a few high-profile bug farm bankruptcies have shaken potential buyers’ confidence in the industry.

Ynsect, a buzzy French start-up, is among those in the midst of a reorganization, after failing to raise enough money and running into issues with the mealworms it was working with.

“If customers are seeing that some players are failing, they start asking, ‘Is it worth investing in this solution?’” said Ray, the Innovafeed CEO.

Farming fly larvae may prove more promising than rearing mealworms. Innovafeed has struck deals with U.S. feed giants ADM and Cargill to raise money, market its products, and build a new bug farm in Decatur, Illinois, next to the world’s biggest corn processing plant. Dutch start-up Protix has inked a deal with Tyson to build a rival U.S. fly farm. Although Innovafeed’s Nesle farm is now the world’s biggest, the race is on to surpass it.

If the industry can expand production from a few thousand tons of protein a year to millions, it could grow large enough to make a dent in the environmental damage that comes from landfills, incinerators, foraging wild fish and clearing forests for new farms.

Innovafeed has identified 30 to 40 potential bug farm sites in Europe and 50 more in the U.S. that are next to a source of food waste and heat and have enough room to build, Ray said.

But in addition to these industrial sites, experts say insect farms could one day collect food waste from grocery stores or be built alongside composting facilities.

Start-ups already sell homeowners countertop kits to raise insects on kitchen scraps. Some insects can even eat plastic.

“Being able to incorporate insect farming into waste management and use the by-products as safe and nutritious ingredients would be great, rather than hauling so many trucks of trash out to the landfill,” said Christine Picard, a biologist who studies insects at Indiana University at Indianapolis. “If this really takes off, I’d love to see this implemented at multiple levels [including] community areas where you could bring your food waste to be recycled.”