Read our COVID-19 research and news.

Dried and crushed mealworms could be fed to cattle, pigs, poultry, and fish.

Dried and crushed mealworms could be fed to cattle, pigs, poultry, and fish.


Feature: Why insects could be the ideal animal feed

Mick Grant is a farmer in Roos, U.K., a burly fellow with strong hands and a quick smile. His great-grandfather started out with a shop and two cows. Out of that grew Elm Farm, a 450-hectare estate on which Grant is raising pigs and growing wheat, peas, and oil seed rape. Recently, Grant has added a new species of livestock: housefly larvae, also known as maggots.

In two blue shipping containers a short drive from the farmhouse, Grant is raising them by the tens of thousands. They grow on manure from a nearby chicken farm—the fresher the better, Grant says: “As it gets older it crusts and gets fungus in it.” Maggots from old manure, he says, “are not as good a maggot as they are at the beginning.”

Grant has produced hundreds of kilos of dried maggots in the last few months as part of an E.U.-funded research project called PROteINSECT. They are now being fed to fish, pigs, and chickens in large trials designed to answer an increasingly urgent question: Are insects the animal feed of the future?

Some scientists are convinced the answer is yes. The world’s appetite for meat is growing, and the production of animal feed is an increasing strain on land and water. Insects could provide much of the protein animals need at a much lower environmental cost; many insect species can feed on manure, like Grant’s maggots, or other types of organic waste, such as leftover food, offal, and grains discarded by breweries.

Regulatory agencies are beginning to weigh the benefits against potential safety risks, including the possibility that insects might accumulate environmental toxins or even transmit diseases to the farm animals that eat them. On 8 October, the European Food Safety Authority (EFSA) in Parma, Italy, released its first report on the risks of using insects as food and animal feed. It concluded that the risks depend on the insect species used—and that more studies like PROteINSECT are needed before livestock or fish are switched to this new diet. But in other countries the brave new world of industrial-scale insect farming is already on view.

THE BEST WAY TO TURN INSECTS into food is simply to eat them—and in many countries people already do. More than 2 billion people occasionally cook caterpillars, boil beetles, or marinate maggots as part of their traditional diet. In Southern Africa, 9.5 billion mopane caterpillars—named for their favorite tree—are harvested every year for human consumption, and in Uganda, a kilogram of grasshoppers is more expensive than a kilogram of beef.


Environmentally speaking, it’s a great choice, says Arnold van Huis, an entomologist at Wageningen University in the Netherlands who co-authored an insect cookbook. Insects produce body mass at an astonishing rate, in part because as coldblooded animals they don’t need to expend energy on regulating their body temperature. Crickets need only 1.7 kilograms of feed to gain a kilogram of body weight; a typical U.S. chicken consumes 2.5 kilograms, pigs 5 kilograms, and cattle 10 kilograms. Another advantage: Most insects can be eaten whole. Only about half of a chicken or a pig is edible; for a cow the fraction is even less. As a result, raising a kilogram of insect protein produces less CO2 than rearing pigs or cattle, Van Huis says, and takes up only one-tenth the land.

Edible species, of which there are some 2000, are high in protein and rich in micronutrients such as iron and vitamins, several studies have found. A 2012 report by the Food and Agriculture Organization of the United Nations (FAO), co-authored by Van Huis, noted “the huge potential that insects offer for enhancing food security.”

But beyond the safety unknowns, putting insects on the menu faces a bigger obstacle, Van Huis says: “Most people are simply disgusted by the idea of eating insects.” Feeding insects to livestock may have a lower environmental payoff but could be easier to sell to the public, and it makes the safety concerns less acute. (And, who knows, insect enthusiasts say, once farm animals start eating insects, humans might begin to find the idea less repulsive.)

Studies suggest that many animals do just fine on insects—which after all are a natural staple for creatures from chicken to trout. A 2014 review by FAO scientists of feeding trials conducted on catfish, tilapia, rainbow trout, and several other fish species, as well as crustaceans, chickens, and pigs, concluded that insect meal could replace between 25% and 100% of soymeal or fishmeal in the animals’ diets with no adverse effects. Most insect meals were deficient in calcium and the amino acids methionine and lysine, but those can be added cheaply. The authors noted that the aroma and texture of fish did not change when they were fed on black soldier fly larvae.

  	Many people find the idea of eating mealworms repulsive. Feeding them to animals avoids that problem.

Many people find the idea of eating mealworms repulsive. Feeding them to animals avoids that problem.


EUROPEAN FARMERS have little experience raising insects, but Grant didn’t have to start from scratch. Elm Farm has produced bluebottle larvae for decades, as bait for recreational fishers. They grow on abattoir waste—kidneys, livers, and hearts, glistening in nauseating reds, greens, and browns. Within a few days they’re covered by thousands of maggots, as if they had come back to writhing, pulsing life.

These larvae are an important moneymaker for Grant in the summer. But with the houseflies he is raising next door, he hopes to break into an even bigger market. In one of the shipping containers, thousands of flies buzz in a huge wooden compartment. Early in the morning, a farmhand places trays of fresh chicken manure on the floor of the container. For 2 hours, the flies are allowed to lay their eggs on the manure. Then, the trays are put inside the other container to hatch.

Larvae start hatching from the eggs within hours. They feed on the manure, which is kept moist, and slowly burrow into it. After a few days they move toward the sides of the tray; that means they are ready to harvest. Some of the maggots get a little extra nutrition: fish scraps. Grant uses those maggots to replenish the stock of flies next door. “The fish just gives the flies a certain va-va-voom,” he says. “They are just fitter and lay more eggs.” But most of the maggots are destined to be animal feed. They are sieved from the manure, then dumped into a cement mixer, where they are dried and left to fall apart, resulting in a fine insect powder.

For now, it’s all for research purposes. But Grant likes to imagine a building where all of this is automated so that he can churn out tons of animal feed. “The potential is huge,” Van Huis says. In 2014, the world produced about 980 million tons of feed, worth about $460 billion. With meat consumption growing, those numbers will only rise. Already, more than 80% of the world’s soybeans are used as feed; their cultivation takes up huge amounts of land and water. Insect meal could never replace soy feed entirely, but it could take some pressure off, says PROteINSECT coordinator Elaine Fitches, a researcher at the Food and Environment Research Agency (FERA), a partly privatized U.K. government institute in York. It takes about a hectare of land to produce a ton of soy per year; the same area could produce up to 150 tons of insect protein, she estimates.

Insect protein could make an even bigger impact in aquaculture, which consumes 10% of the world’s fish production as feed for other fish. The availability of fishmeal has been erratic and its prices are rising rapidly, says Jason Drew, a U.K. entrepreneur—from about $500 per ton in the 1990s to $1500 to $2500 in recent years. “Companies are looking for solutions to the looming protein crisis, Drew says. “I think insect protein will replace fishmeal. We can then leave this food source at the bottom of the food chain, where it should be—in our seas.”

Drew is one of the founders of AgriProtein Technologies, a company in Cape Town, South Africa, that many observers agree is furthest along in rearing insects at an industrial scale. With $11 million from the Bill & Melinda Gates Foundation and private investors, the company has built a huge factory next to Cape Town International Airport that is now ramping up production. Once it reaches capacity, soldier fly larvae will consume 110 tons of organic waste daily to produce 24 tons of maggots. Dried and ground to a powder, they will be sold to South African farmers as feed at a lower price than fish meal, Drew says. Nothing prevents him from taking his product to the market, and he already has plans for a second factory. Drew thinks maggots will make him a millionaire.

REGULATORS IN EUROPE and the United States, however, still have concerns. In the United States, using insects as feed is allowed in some states but not others. EnviroFlight, a company based in Yellow Springs, Ohio, is rearing black soldier fly maggots and selling them as food for pets and zoo animals. The company is working with the Food and Drug Administration to prove it’s also safe to feed its larvae to animals eaten by humans. Feeding trials, mainly of fish, are underway, and nationwide approval could come as early as September 2016, predicts EnviroFlight’s founder and director Glen Courtright. “That would open the flood gates.”

Europe is warier, in part because of the outbreak of bovine spongiform encephalopathy (BSE), better known as mad cow disease, in the 1980s and 1990s. BSE is caused by misfolded brain proteins. It spread among cows because they were fed proteins extracted from the remains of other cows, and a few hundred people who ate infected beef caught a fatal human form of the disease, variant Creutzfeldt-Jakob disease. In response, the European Union banned the feeding of almost any type of animal protein to farmed animals.

No one thought of insects at the time, but today, the regulation is holding back development, complains Antoine Hubert, a French scientist who co-founded Ynsect, a company that aims to rear insects for feed and other applications. Because insects and mammals are so distantly related, the risk of prions or other pathogens making the jump is much smaller than it is between mammals, Hubert argues.

In 2013, the European Union relaxed the rules a bit to allow the use of animal proteins in aquaculture. But there is one problem: Animals used as fish feed have to be killed in a certified slaughterhouse with a welfare officer present, a rule clearly not written with maggots in mind. As a result, fish farms can now feed their animals chicken offal but not insects—even though many fish species eat insects in nature but not chicken. “That’s just absurd,” Hubert says.

Hubert is now lobbying for changes in the regulations through the International Platform of Insects for Food and Feed, which he founded in April together with representatives of AgriProtein and companies from France, Germany, and the Netherlands. The European Commission is paying attention: Also in April, it asked EFSA, its food watchdog, to look into the risks posed by the use of insects in food and feed. The resulting report, issued last week, mentions the buildup of chemicals such as heavy metals or arsenic as one possible risk. It also discusses infectious diseases, but finds that the risks aren’t higher than with other sources of animal protein.

  	Mick Grant, a farmer in the United Kingdom, has long raised bluebottle larvae for anglers.

Mick Grant, a farmer in the United Kingdom, has long raised bluebottle larvae for anglers.

Kai Kupferschmidt

Insects aren’t even known to develop prion diseases, the report notes, and it agrees with Hubert that any bacteria or viruses that harm insects are most likely harmless to humans. Insects could conceivably pick up pathogens of fish, birds, or mammals through their diet and passively spread them, but there are ways to mitigate those risks, the report says, such as carefully choosing the insects’ food source.

On many issues, however, there’s simply not enough information. There are reports of allergic reactions in humans after eating insects, for instance, and even a case of anaphylactic shock. But such allergic reactions have never been reported in farm animals, although they should be monitored for that, the authors write.

MICK GRANT’S MAGGOTS could help provide more answers. At FERA, scientists have pureed the maggots and investigated them for pesticides, heavy metals, and traces of antibiotics and growth hormones. “Anything that we find on a farm could find its way into the maggots and in our food chain,” says Michael Dickinson, a scientist at the institute. “But we have not found any red flags so far.” The maggots are now being fed to pigs and chickens in Belgium. The growth of the animals as well as their health and the meat quality is compared with animals on a standard diet. By the end of the year, results from these trials should be available for EFSA to take into account.

Whether maggot-fed meat eventually makes its way to the table will depend in part on public acceptance—and Hubert worries that PROteINSECT’s use of manure as a food source will not help. “The public won’t accept feeding insects on manure,” Hubert says. (Ynsect, his own company, only uses food industry byproducts that are allowed as feed.)

Mick Grant, for his part, sees no problem. For him, insects are all about efficiency. “If you can use waste to make something, it makes more sense than anything, doesn’t it?"