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Black Soldier Flies: Inexpensive and Sustainable Source for Animal Feed

another photo of Roseanne at the farm with bins of black soldier flies for her farm

Rosanne Mwangi scoops up two handfuls of squirming Black Soldier Fly larvae. “Brown, live gold,” she says with a broad grin.

The flies she refers to as gold are alive only for a fleeting six weeks. But during that time, they reproduce generously, laying 500-plus eggs in a single batch, and are fairly indestructible, having been known to survive up to two hours submerged in pure rubbing alcohol. They eat in a writhing mound, thousands sharing a single serving of nearly any kind of organic waste.

The single most important fact about Black Soldier Flies (BSF) may be that in the larvae stage, they have the Superman-like ability to transform that waste into high-quality protein. Used as alternative protein additives in animal feed, this translates into an inexpensive, clean and sustainable food source—especially important as farmers, along with global economies, struggle to recover from the financial impact of the Covid-19 pandemic, including food shortages.

“The BSF is a path to improving household incomes with a readily available resource, and that is really exciting,” says Mwangi, a mother of three who lives in Muranga County, a farming community in Kenya’s Central Highlands.

BSF To Alleviate Poverty & Promote Food Security

The Rockefeller Foundation has partnered with the International Centre of Insect Physiology and Ecology (icipe) on a project to test business models for scaling insect-based protein feed in poultry and pig farming and aquaculture in Kenya. The goal is to help alleviate poverty, promote food security and improve the overall health status of smallholder farmers. An international science research institute headquartered in Nairobi, icipe’s mission is to use insect science for sustainable development.

Icipe researched more than 28 insect species, including locusts and crickets, before settling on the BSF larvae as the best way forward. “Black Soldier Flies are exceptional,” says Dr. Chrysantus Mbi Tanga, an icipe research scientist specializing in insect-based feed.

Rosanne Mwangi says her pigs are ready for market a month or two earlier when given BSF feed.

The icipe team also made sure they had a large pool of potential consumers and significant need. Studies indicate about 90 percent of farmers and 85 percent of feed producers in Kenya are ready to use insect-based feed. The annual supply of dried BSF larvae for feed formulation in Kenya is about 3,600 metric tons, but icipe estimates the current demand at about 90,000 metric tons. Since 2015, icipe has trained more than 5,000 farmers across Kenya in how to raise and use BSF as feed supplements.

Some 75 percent of working Kenyans make all or part of their living by farming, including some 800,000 smallholder farmers. Currently, 46 percent of the population of about 54 million people live on less than 1 U.S. dollar a day, 36.5 percent are food insecure and 35 percent of children under five are chronically malnourished.

Careful Research Led to BSF-Based Feed Production

Increasing BSF production and use in feed has several direct advantages. The first is that it is easier on the pocketbook. “The most expensive component of raising animals is the protein cost in feeds, which accounts for 60 to 70 percent of the total production cost,” says Dr. Tanga. “BSF are a lot more affordable. They grow on organic waste and within two weeks you can harvest them.” For Mwangi, using BSF as feed has resulted in about a 20 percent increase in earnings.

Woman scoops up Black flies out of their farm
Mwangi raises BSF on her farm to feed her chickens and pigs.

Secondly, Dr. Tanga says, “our research showed the BSF larvae are even better for the animals than conventional feed. Scaling up insect-based technologies will have a huge impact in improving poultry, fish and pig production.”

That means better quality meat and eggs, and faster to market. Mwangi says her free-range chickens, which normally take about 24 weeks to be market-ready, are now going to market at 16 weeks. And her pigs are ready for market in about six or six-and-a-half months, saving her one to two months.

Thirdly, BSF larvae has the advantage of being solely for animal consumption. Traditional feed is made from fishmeal and soybeans, and the animals are in a sense competing with humans for this food.

And finally, BSF production creates job opportunities for youth and women who produce the feed. Mwangi employs seven people fulltime, and brings in extra workers during peak harvesting periods

Turning Waste into Value

  • infographic on insects and farming/ agriculture

Here’s how it works: the BSF eggs are placed in tent-like structures along with organic waste where they incubate for three days and then hatch. Pre-pandemic, Mwangi was using potato waste, but has since switched to over-ripe avocados because they have become more readily available. The larvae begin feeding on the waste immediately.

They grow over about 14 days and then all but 10 to 20 percent are harvested into feed. The remaining BSF perpetuate the colony. Within two weeks, they pass through the pupae stage before becoming flies. The flies live for about 10 to 16 days more on a diet of water only, and during that time they lay the eggs that begin the process again. Another outcome of the process is organic frass fertilizer, which can be sold as an additional value-added product or used in farmlands for increased crop productivity.

Taking something that is considered to be waste, and turning it into a higher value product while avoiding the use of chemical additives, Mwangi says, is her contribution to global sustainability and climate-smart agriculture.

Mwangi’s parents were social workers, but her sister grows potatoes and she raises chickens and pigs. “It is really rewarding to see things grow,” she says. “It is a job that makes economic sense but you also have time to do other things. So now, I am teaching other farmers about how to raise BSF and use the larvae as feed supplements. It can really improve the household income of smallholder farmers.”

Mwangi’s youngest child, an eight-year-old daughter, “is always with me, tugging along at my skirt,” Mwangi says with a laugh. “She is a farmer in the making, and the Black Soldier Fly is most definitely the future.”