Will It Smell, and Will It Bring Flies? Eight Myths About On-Site BSF Treatment

Every facilities manager, sustainability lead and municipal officer who considers on-site Black Soldier Fly (BSF) bioconversion ends up asking the same handful of questions. Most of them are not about carbon accounting or circular economy theory. They are about the bin room. Will it smell? Will there be flies everywhere? Is it safe to have insects near a kitchen? Is this even legal?

These are fair questions, and they deserve better answers than a sales brochure usually gives. This piece works through the eight concerns we hear most often, separating what the research actually says from what people assume, and being clear about where real limits and responsibilities lie.

Myth 1: "Anything that eats food waste is going to stink"

Odour from food waste comes mainly from anaerobic decomposition: when wet organic material sits without oxygen, it produces volatile fatty acids, hydrogen sulfide, amines and ammonia. That is why a full bin left in a loading bay for three days smells so bad, and why landfills and poorly managed compost piles are the classic sources of complaints.

BSF larvae (BSFL) change those conditions. They are voracious feeders that constantly move through the substrate, breaking it up, aerating it and consuming it quickly, so food waste spends far less time in the anaerobic state that generates most odour. Research on greenhouse gas emissions points the same way. A study by Mertenat and colleagues at Eawag, measuring emissions directly from BSF treatment units, found direct CO₂-equivalent emissions roughly 47 times lower than those of open windrow composting of the same biowaste, and a life cycle assessment (LCA) in which composting had about double the global warming potential of the BSF facility per tonne of wet waste.

That does not mean zero odour. Ammonia is released as larvae process protein-rich waste, and any system will smell if it is overloaded, too wet, or fed material it was not designed for. The honest answer is that odour is a management variable, not an inherent property of insect treatment, and that a well-run BSF process generally produces far less nuisance than the bins and haulage it replaces.

Myth 2: "You are inviting a fly infestation"

This is the most common worry, and it stems from confusing the black soldier fly with the house fly. They are different insects with very different behaviour. The University of Florida's entomology extension service notes that BSF adults are "not usually considered a pest," have no stinger and pose no danger to people. They are not drawn to human food or living spaces the way house flies are, and they are not known as disease vectors (although, like many insects, they are a potential mechanical carrier of microbes, which is why containment and hygiene still matter).

It is also worth correcting an older myth here. You will often read that adult BSF "don't eat at all." Recent work, including a 2025 study in the Journal of Insects as Food and Feed, shows adults do take liquid food through sponging mouthparts and live longer when they do. What has not changed is that they do not bite, do not seek out kitchens, and do not behave like nuisance flies.

In an enclosed, decentralized treatment unit the practical point is simpler still: the process is about larvae, and a properly designed system keeps the life stages contained. Ask any vendor how adult flies, breeding and escapes are managed. It is a reasonable question and the answer should be specific.

Myth 3: "Insects plus food waste equals a pathogen risk"

Food waste already contains bacteria; the question is whether treatment increases or reduces the risk. Here the evidence is encouraging. Lalander and colleagues at the Swedish University of Agricultural Sciences reported a 7 log₁₀ reduction of Salmonella spp. in eight days in a batch BSF system treating faecal sludge, a far more challenging substrate than commercial food waste, and later continuous-reactor work by the same group again observed lower Salmonella concentrations in the treated material.

Regulators do not rely on larvae alone, and neither should operators. In the EU, Regulation (EU) 2021/1925 defines insect frass and requires it to be heat-treated at 70 °C for 60 minutes and to meet microbiological standards before it can be placed on the market as a fertiliser or soil improver. That kind of validated post-treatment step is the right benchmark for frass fertilizer wherever you operate.

Myth 4: "It will attract rats and other pests"

Rodents are attracted to accessible food. The biggest pest risk on most sites is the status quo: overflowing bins and food waste waiting for collection, sometimes for days. Treating waste on site, close to where it is generated, shortens the time that food waste sits around as an open food source. As with any waste system, good housekeeping, sealed storage and regular inspection still matter, but a contained treatment process is usually an improvement on a loading dock full of wheelie bins.

Myth 5: "It's not legal to do this"

Regulation is real, but it is not a wall. It is a set of rules that differ by what you put in and what you take out. Most frameworks distinguish three questions: Is the site permitted to treat organic waste? What substrates can be fed to farmed insects? And what can the outputs (larvae, insect protein, frass) be used for?

The EU is the strictest example. Insects farmed for feed are treated as farmed animals, so catering waste and material containing meat or fish are generally not permitted as substrates for insects destined for the sustainable animal feed chain, while insect frass now has its own legal definition and processing standard. Rules elsewhere, including across Asia-Pacific, vary considerably and are evolving. The practical takeaway is to match the system and the end use to local rules from the start, and to treat regulatory alignment as part of system design rather than an afterthought. Policy momentum also matters: this month's COP31 in Antalya is centred on waste, with the presidency pushing a target to halve the growth in global waste by 2035. Organic waste diversion and methane emissions reduction are rising up the agenda, not down.

Myth 6: "It needs a big industrial site"

Large centralized insect factories do need big buildings, and several high-profile megafactories have struggled financially. But that is a feature of the centralization model, not of BSF bioconversion itself. Decentralized systems are designed to work at the scale of a single kitchen, campus, market or processing line, so the waste is treated where it is produced. That saves land and also removes the collection trucks, transfer stations and long-haul trips that make centralized treatment carbon-intensive. For space-constrained cities in particular, localization is often what makes organic waste treatment possible at all.

Myth 7: "It must be more expensive than just paying a hauler"

Hauling looks cheap because its costs are spread out and partly hidden: collection fees that rise with fuel and labour, landfill levies and gate fees, and, increasingly, the Scope 3 emissions that corporate reporters now have to disclose under the GHG Protocol and defend to auditors and SBTi validators. Extended producer responsibility (EPR) schemes and organic waste diversion mandates keep pushing these costs up.

On-site BSF treatment changes the equation in two ways. It reduces the volume that has to leave the site, and it produces outputs with value, namely insect protein for animal feed and frass fertilizer for soil health and regenerative agriculture, instead of a disposal bill. The right comparison is not "machine versus truck" but total cost of ownership, including avoided haulage, avoided disposal fees and the value of recovered resources. Ask for that comparison using your own waste volumes.

Myth 8: "It's an experimental technology"

BSF bioconversion has been studied for decades and is now one of the most researched insect-based waste valorization pathways in the world, with a literature spanning pathogen control, emissions, LCA, feed safety and fertiliser value. The industry has had real setbacks, mostly in capital-heavy centralized models, but the underlying biology is well understood. What differs between systems is engineering, operation and fit with local regulation, which is exactly what a buyer should evaluate.

What to ask before you buy

The myths above have a common thread: the concerns are legitimate, but they are about how a system is designed and run, not about whether BSF bioconversion works. Before committing, ask any provider for: their approach to odour and moisture management; how adult flies and life stages are contained; how outputs are post-treated and what standards they meet; which substrates the system accepts under your local rules; realistic space and servicing requirements; and a total-cost comparison against your current waste contract.

B-BOX was built around exactly these questions: a decentralized, contained BSF treatment unit that turns food waste into value where it is generated, cutting methane emissions, haulage and land use while closing the loop toward a circular economy. If your team is weighing on-site treatment, we are happy to work through these questions with your own numbers.

Sources

• Mertenat, A., Diener, S., Zurbrügg, C. (2019). Black Soldier Fly biowaste treatment – Assessment of global warming potential. Waste Management. (Eawag)

• University of Florida IFAS Extension, Black Soldier Fly, Hermetia illucens (EENY-461 / IN830).

• Barrett, M. et al. (2025), Journal of Insects as Food and Feed, on adult BSF feeding preferences and longevity.

• Lalander, C. et al. (2013). Faecal sludge management with the larvae of the black soldier fly. Science of the Total Environment; Lalander, C. et al. (2015). High waste-to-biomass conversion and efficient Salmonella spp. reduction using black soldier fly for waste recycling. Agronomy for Sustainable Development 35, 261–271.

• Commission Regulation (EU) 2021/1925 amending Regulation (EU) No 142/2011 (insect frass); IPIFF fact sheet on insect frass (2021).

• Health Policy Watch (2026), "Clean Electricity, Waste and Construction Set to Top COP31 Agenda."