Black soldier fly larvae cut biowaste volume by up to 80% — but EU feed rules bar the gate fees

Black soldier fly larvae working in their thousands can cut biowaste volume by up to 80% within seven to fourteen days. That throughput figure, from researchers at Eawag, the Swiss Federal Institute of Aquatic Science and Technology, sits at the centre of a technology whose economics in Europe are decided less by biology than by regulation.

The market context is stark. Global funding for insect protein companies fell from USD 472 million in 2022 to USD 170 million in 2024, and several operators closed their businesses. The black soldier fly, or Hermetia illucens, was oversold, one reading goes. The less obvious reading, advanced by the Eawag group, is that the failed industry had quietly abandoned the thing the fly is actually good at: biowaste management.

Why does feedstock law decide the business model?

In the EU, insects may legally eat food waste only before it legally becomes waste. The UK and US arrive at much the same place by different routes. Catering and kitchen waste is barred; supermarket and factory surplus without meat or fish is not.

A European plant therefore runs on brewers' spent grain, bakery surplus and vegetable trimmings — plant material, with narrow exceptions for milk, eggs, honey and non-ruminant fats. All of it is genuinely upcycled. But that material already has buyers and a price, so the operator pays for feedstock instead of being paid a gate fee to take it. That is the entire economic problem in one line.

"Very restrictive regulations can make it difficult to use BSF to its full potential," said Dr Daniela Peguero, who works with a group led by Dr Christian Zurbrügg of Eawag. "But having no framework also creates uncertainty. You need standards because ultimately, we're producing something that may enter the feed or agricultural system. The challenge is finding that balance, protecting safety without regulating the technology so heavily that it becomes impractical."

What did the UK trials find?

The UK has at least tested the question. The Food Standards Agency commissioned research rearing larvae on four barred waste streams, including hospitality kitchen waste and poultry manure. The results were not a clean pass. Pesticide residues exceeded limits in some larvae; E. coli exceeded limits in frass from catering waste. As of January 2026, Defra restated the ban. What has changed is the market, not the menu.

Where does the technology fit?

Peguero's group runs projects in Uganda, Malawi and Indonesia and positions BSF not as a silver bullet but as a complement to composting and anaerobic digestion. "It's really about finding the right technology for the waste stream and the local conditions," she said.

The operating envelope is specific. Native to tropical and subtropical environments, the larvae want 25–32°C and 60–70% relative humidity, which makes tropical countries attractive venues. Substrate quality matters as much as climate. "Ideally, the waste coming into a BSF facility should be 100 per cent organic and as pure as possible," Peguero said. Mixed municipal waste is unsuitable; heavy metals can accumulate in larvae or persist in frass. For operators without lab access, she prescribed prevention: know the waste source, inspect incoming material visually, keep records, reject anything suspicious.

Larvae favour nutrient-rich material with digestible proteins and carbohydrates. Very fibrous waste needs physical or biological pre-treatment. Composting handles fibre better; anaerobic digestion produces renewable energy.

What does a facility output?

Two products. The larvae, rich in protein and fat, go to animal feed, with further outlets in pet food, cosmetics and biobased products including oils and chitin. What the larvae do not eat becomes frass — residual matter, excreta and shed exoskeletons — which after roughly four weeks of composting becomes a soil amendment. "You're not just getting rid of waste, you're transforming it into two useful products and recovering nutrients that would otherwise be lost," Peguero said.

The market is growing but uneven. Under the SWIFT project, funded by the Swiss Agency for Development and Cooperation and the Swiss National Science Foundation, surveys of farmers in Malawi and Uganda found broad interest in BSF products constrained by awareness. Demand splits by region: pet food pulls in Europe; exotic animals, including songbirds, pull in Indonesia. Pet food pays a premium that feed markets do not.

What scale works?

The flexibility is unusual. Under the BUGS project, funded by the Climate and Clean Air Coalition, the group developed SIMBA — a Simplified BSF Approach processing around 250 kg of waste per week. Facilities handling 10–15 tonnes per day exist, and highly industrialised plants reach up to around 700 tonnes per day. "There really isn't one ideal size," Peguero said. Operators can breed flies themselves or buy eggs from a central breeding facility; adults need only water, warmth, space, light and laying structures.

Failures follow patterns. European companies have struggled with high energy and capital costs, scaling and restrictive regulations. Donor-funded projects collapse when funding ends. Peguero's group has published a pre-investment guide covering the enabling environment, waste availability, operating conditions and product markets.

Europe has waste volume, conditions and markets. The regulatory framework is the missing fourth factor — and it is the one no operator can solve alone.