Jane Craigie: Black Soldier Fly farming: a quiet rural revolution?

Black Soldier Fly (BSF) farming has come up three times during my recent travels in the US and Kenya, where its advocates are gaining traction and some interesting business models. However, it was at the last Nuffield Farming Conference at the P&J Live that the potential of this enterprise finally crystallised for me thanks to David Tavernor who studied the sector for his Nuffield scholarship. 

As a biological waste management, and both a protein and fertiliser production system, the BSF capabilities are incredible. The larvae contain between 35-55% percent protein, grow from egg to harvestable size in just 15 to 18 days; if a calf grew at the same rate, it would reach adulthood in two weeks. Their capacity for managing waste is impressive too, for example, 10 tonnes of organic manure can be transformed into two tonnes of larvae and two tonnes of frass - an organic fertiliser - in four weeks, while conventional composting takes four to six months. Add a gate fee for local authorities, food manufacturers or processors to dispose of their waste into the business model and David Tavernor says the economics really start to stack up. 

Frass alone is compelling. With a nutrient profile similar to chicken manure but considerably lower moisture and odour, and a reduced pathogen and heavy-metal risk, it offers farmers a stable, safe fertiliser option. 
The larvae themselves are immensely valuable as a high-quality protein source for poultry, pigs, fish and pets. For farmers conscious about circularity and their carbon footprint, the strategic value lies in something much simpler: producing home-grown protein and reducing reliance on imported soy and fishmeal.

Yet despite all the positives, there is a big but. The UK’s regulatory landscape remains one of the biggest barriers, unlike in the US and Africa where legislation is more enabling. Here, a loophole in the law means that farmers are allowed to feed live larvae to certain livestock, but the moment larvae are made into, say a dried meal, they fall under strict rules on processed animal protein. Meal and oil are permitted for aquaculture and pet food, but not yet for poultry or pigs, where they could offer so much feed value. This single legislative bottleneck drastically limits commercial scaling, even though the science supports safety when appropriate substrates and traceability are used.

The constraints extend to feedstock rules too. EU-derived legislation still prohibits the use of substrates such as catering waste, fish offal, manures and mixed municipal waste. David’s international research showed clearly that countries with more flexible, risk-based frameworks are already developing thriving BSF industries.

Economically, the picture is promising but far from straightforward. Drying BSF larvae remains energy-intensive, as much as 15% of final product value, compared with soybean drying at around 3-5%. Without scale, reliable waste contracts or improved drying efficiency, BSF farming remains a thin-margin business.

Despite this, the practicalities on farm are far more approachable than many might expect. A BSF unit typically requires a temperature-controlled space, 26 to 32oC is ideal, so the enterprise could run well alongside a pre-installed biomass facility along with a dependable supply of legal feedstock and a simple infrastructure of trays or stacked racks. Basic hygiene and biosecurity are essential, but labour demands are modest. Many farmers abroad have adopted small systems in converted sheds or insulated containers, scaling up only once supply chains are secure. 

Hearing David Tavernor present his findings, I was left thinking what potential BSF farming could offer as a ‘bolt-on’ enterprise for the North East’s farming and food sector, particularly for businesses looking to spread their risk, or take more control of their own protein and fertiliser supply. The biology is proven. The markets could be good. The systems are practical. What remains a barrier is the regulatory changes needed to bring this industry to life in Scotland.