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The Black soldier flies (BSF), Hermetia illucens (Linnaeus), is a common fly of the Stratiomyidae family. They are commonly found throughout the Western hemisphere and the Australian region. Once the eggs hatch, the larvae find whatever waste they can and immediately start to consume it. Two weeks later, the larvae have reached full maturity when their environmental conditions are favorable.
The interesting point is that the larvae are very efficient to convert protein which can be used once converted and transformed (cleaned/washed/dried/grinded…) as animal feed… Moreover, the biowaste (frass) collected from the BSF can be used as an organic fertilizer. The process is called bioconversion. In 2050, proteins from insect could represent about 10-15% of the animal feed market mostly for the aquaculture and the poultry farming industries (feedstock).
Black soldier fly growing conditions
The Black soldier flies (BSF) are extremely sensitive to their environments; thus, their conditions need to be monitored extensively to ensure the highest yield is obtained. Considering black soldier flies are an equatorial and generally a warm-season temperate species, their lifespan is dictated by how warm their environment is. A temperature of 27°C (80.6°F) for both males and females seems to be ideal for the growth and development of flies at different stages (Tomberlin, 2009).
As previously stated, the BSF are extremely temperature sensitive. With this, they are also highly receptive to humidity. This variable has considerable ramifications on egg hatching. Moreover, the amount of direct sunlight is an important factor to increase the BSF reproduction rate.
Why do we need a greenhouse to grow black soldier fly ?
The multispan greenhouses offer a lot of advantages to grow BSF for all stages of the insect development (egg hatching, young larvae, mature larvae, adult flies : reproduction).
Indeed, for the reproduction phase, a wide and high greenhouse will provide enough volume for the flies mating. The BSF adults have special receptors (vision), the reproduction rate is higher depending of the light penetration inside the growing area therefore a proper design and plastic covering on the greenhouse roofing will help to produce more eggs. What is more, it is possible to control the top vents in order to have an efficient passive ventilation inside the greenhouse. All cladding and windows (= greenhouse vents) can be covered with an insect-proof net in order to protect the BSF from the outside pests like the domestic fly or small birds.
Optimal climate conditions (T°C, HR%, light, ventilation m3/h) are also very important for the nursery and the growing larvae phases to promote a fast growth. For example, from 1kg of eggs, in less than 2weeks, it is possible to produce about 6 tons of larvae. The growth speed is tremendous. The control of the airflow inside the growing area is a key factor to manage the temperature, and humidity levels also the insects’ gas emissions concentration.
In short, growing BSF under greenhouses can be interesting:
_ to save on costs compare to a standard building/factory to start quickly your project ;
_ to have more flexibility to reduce or extend the growing area surface adding new span or by lengthening the existing ones ;
_ to have a lot of volume under the greenhouse to grow BSF larvae on vertical trays and have enough have enough surface for adult reproduction ;
_ to create the perfect climatic conditions inside the greenhouses through a climate computer, probes and equipment (circulation fans, extractors, shading screens, fogging…) ;
_ to protect the BSF from the outside predators and pests selecting the right covering (film, polycarbonate, PVC, tarpaulin, glass…) on the greenhouses roof and cladding depending the project location ;
_ to dry the biowaste (frass) collected from the BSF growing phase in order to make an organic fertilizer ;
The greenhouse type selection to grow Black Soldier Flies (BSF) will depend of the project location (environment, site topography, wind speed, pluviometry…), your budget and other factors such as the growing system (vertical/horizontal…).This can be low- / mid- or even high-tech depending on the production strategy.
Indeed, a sufficient amount of bio-waste of constant quality nearby will be necessary before launching a project as well as an analysis of the needs in proteins and “organic” fertilizers in the region before implementing the project. In fact, it is a key point to sell the production while keeping in view to reduce the costs. transport costs (carbon footprint) and logistics.
An analysis of all those parameters must be done before implementing your future greenhouses.