What is this tool intended for?

The SIMBA Reproduction Unit SOP guides operators through all tasks required to maintain a continuous, self-sustaining BSF colony at small scale. The reproduction unit is the stage that produces the young larvae (7-day-old larvae, or 7-DOL) that Feed the grow-out unit. Without a functioning reproduction unit, there are no larvae to convert organic waste. The SOP’s purpose is to standardise all reproduction tasks, egg collection, hatching, larval counting and rearing, prepupae collection, pupation, and adult fly management in love cages, so that a reliable, consistent weekly supply of 300,000 7-DOL is produced with minimal labour.

The SOP is explicitly Designed for the SIMBA scale: a part-time operation requiring around 4–6 hours of labour per week across two working days, producing enough young larvae to supply five grow-out units, each processing approximately 50 kg of organic waste per week (250 kg total), and yielding 30–40 kg of fresh larvae and approximately 100 kg of frass weekly across the combined system. The full reproduction cycle from egg to 7-DOL takes 8 weeks when running at full capacity with four love cages operating simultaneously.

How does this tool work?

The SOP is a printed or downloadable PDF manual structured around the three divisions of a BSF reproduction unit, each corresponding to a distinct phase of the BSF lifecycle:

•        Egg division: Female flies lay eggs into structured wooden sheets called eggies, which are placed inside netted love cages. Eggies are removed twice weekly and placed over hatchling boxes filled with nutritious Feed (e.g. rice/maize/wHeat bran, chicken Feed, spent grain) at 70% moisture. Neonates hatch over 3–4 days and fall into the Feed — a system called the hatchling shower. After a further 3–4 days, 7-DOL are harvested by sampling and counting larvae to determine the weight-to-number ratio, then distributing the required 30,000 7-DOL to nursery containers for the reproduction cycle and the remaining 300,000 7-DOL to the grow-out units.

•        Larva division: 30,000 7-DOL are divided across three nursery containers (~1,500 cm² each), each receiving 10,000 larvae and two Feedings of nutritious substrate over approximately two weeks. Two approaches are described: Approach A (rearing larvae on a controlled nutritious diet within the reproduction unit) and Approach B (using larvae harvested from the grow-out unit, fed briefly until they reach prepupae stage). As larvae reach the prepupal stage they self-harvest by migrating into surrounding collection containers in search of a dry place to pupate. Water is added to the nursery containers to encourage remaining prepupae to leave. Collected prepupae are placed into pupation containers where eclosion into adult flies occurs within 2–3 weeks.

•        Adult division (love cages): 20,000 pupae are distributed across two eclosion boxes placed inside a netted love cage (~75×75×150 cm). The love cage also contains a water container (with a cotton wick for drinking), an attractant container (a slurry of dead flies, nursery container residue, and Feed), and six eggies for egg laying. Flies eclose, mate, and lay eggs over approximately two weeks, after which the love cage is dismantled and washed. Four love cages operate simultaneously at full capacity, with one additional cage reserved for washing.

The SOP includes two annexes: Annex A is an illustrated alphabetical list of all equipment items (love cage, eggies, eclosion boxes, hatchling boxes, nursery containers, pupation containers, collection containers, attractant containers, etc.) with dimensions and functional descriptions; Annex B is a laminated two-week task and schedule checklist covering all general, adult division, egg division, and larva division tasks, Designed to be printed, laminated, and reused.

The SOP is an analogue (PDF) resource. No Software or internet connection is required once downloaded. All calculations use simple arithmetic formulae (e.g. for determining grams of larval mixture needed to obtain a target number of 7-DOL).

Who might use this tool and with which types of stakeholders?

The SOP is intended for:

•        Smallholder farmers who want to maintain their own BSF colony to continuously supply young larvae to their grow-out units, producing Feed for chickens, pigs, or fish from locally available organic waste

•        First-time BSF operators setting up a SIMBA system as a part-time side activity or demonstration project

•        Research centres and universities operating small-scale BSF reproduction units for research purposes, or to supply larvae for experimental grow-out studies

•        Extension workers and trainers supporting farmers or entrepreneurs in establishing and maintaining a BSF colony

•        NGOs and development projects introducing BSF as a sustainable livelihood and waste management solution at community level

The SOP is written in plain, accessible language with clear step-by-step instructions and visual diagrams. It is Designed to be followed directly by farm operators with no prior entomological knowledge, under the oversight of a responsible manager who understands the BSF lifecycle. It can also serve as a training reference for extension agents.

What stages of a process can this tool support?

The SOP supports the daily and weekly operational management of the BSF reproduction unit, specifically:

•        Egg collection and hatching: Setting up hatchling showers, handling and replacing eggies twice weekly, and managing hatchling boxes through the 7-day larval development period

•        7-DOL counting and allocation: Sampling and counting 7-DOL larvae to determine the weight-to-number ratio, calculating the quantity needed for the reproduction cycle (30,000) and the grow-out units (300,000), and distributing larvae accordingly

•        Larval rearing in nursery containers: Setting up nursery containers, providing two Feedings over two weeks (Approach A) or a single short Feeding of grow-out unit larvae (Approach B), and collecting prepupae as they self-harvest into collection containers

•        Pupation management: Placing prepupae into pupation containers, skimming pupae for eclosion boxes, and monitoring pupation progress

•        Love cage operation: Setting up love cages with eclosion boxes, water containers, attractants, and eggies; monitoring fly eclosion, mating, and egg-laying; and dismantling and washing love cages after two weeks

•        Performance monitoring: Tracking key indicators including number of 7-DOL produced per week, prepupae collected per week, pupae count, and egg mass, using the task and schedule checklist in Annex B

The SOP assumes that the grow-out unit is operated according to the companion SIMBA Grow-Out Unit SOP, and that the connection between the two units (supply of 7-DOL from the reproduction unit to the grow-out unit, and optionally the return of mature larvae from the grow-out unit to the reproduction unit under Approach B) is managed by the responsible facility manager.

What skills, capabilities and resources are required to use this tool?

The SOP is Designed to be accessible without specialist training. Requirements include:

•        Around 4–6 hours per week of operator time across two working days

•        A responsible manager with a good understanding of the BSF lifecycle to oversee operations, interpret monitoring data, and respond to deviations

•        Approximately 30 m² of roofed space divided into two adjacent rooms (~15 m² each): one for larval stages (hatchling boxes, nursery containers, pupation containers) and one for adult flies (love cages), with protection from rain, suitable temperature (25–32°C), and humidity (60–80%)

•        Equipment: five love cages (~75×75×150 cm), a minimum of 36 eggies (wooden sheets with pushpins), two hatchling shower racks, hatchling boxes (60×40 cm), at least 30 nursery containers (~60×40 cm), eight pupation containers, collection containers, eclosion boxes, attractant containers, water containers with cotton wicks, a scale, spoons, tweezers, a click counter, plates, and masking tape and a pen for date labelling

•        Nutritious Feed for hatchling and nursery containers (rice/maize/wHeat bran, spent grain, chicken Feed, or similar at ~70% moisture)

No internet connection is required to use the SOP. Access to a device for downloading the PDF is sufficient.

Where can this tool be used?

The SOP is applicable in any location where BSF biowaste conversion is feasible, with a preference for tropical and sub-tropical climates where ambient temperatures and humidity naturally support BSF lifecycle completion without additional climate control. It is particularly suited to:

•        Smallholder farms in Sub-Saharan Africa, South and Southeast Asia, and Latin America where a self-sustaining BSF colony is needed to supply larvae for organic waste conversion

•        Urban and peri-urban settings where a centralised reproduction unit supplies young larvae to multiple decentralised grow-out units (hub-and-spoke model)

•        Research stations and vocational training centres using BSF reproduction as a training or demonstration tool

•        Any context where the SIMBA scale is appropriate: part-time operation, simple equipment, and a weekly output of approximately 300,000 7-DOL to supply around 250 kg of waste conversion capacity

For larger-scale operations (above 1 tonne of waste per day), the SOP refers users to the Eawag Step-by-Step Guide for medium-scale BSF systems, which covers more intensive reproduction management procedures.

Case examples of where this tool has been used

The SIMBA system and its associated SOPs were developed through field experience in the BUGS-AFRICA and SWIFT projects, with partner institutions in Malawi (Soil Food and Healthy Communities/SFHC, Mzuzu University), Uganda (Makerere University, Bioconvision), and across Africa (Africa Circular). The equipment specifications, Feeding quantities, larval densities, and eight-week reproduction cycle described in the SOP were developed and validated through practical trials at small-scale BSF facilities in these contexts.

The SOP is referenced in the BUGS Africa Operators Toolkit (CCAC, 2025) as the recommended standard operating procedure for the SIMBA reproduction unit, and is intended to be used alongside the companion Grow-Out Unit SOP, the BSFL Substrate Navigator, and the SIMBA cost-revenue and GHG emission calculators to support a complete small-scale BSF operation. The SOP is also suitable for research centres that require a standardised, documented colony management protocol for experimental or teaching purposes.