Demand for animal products is rising in the developing world. However, the current practices associated with animal agriculture, such as deforestation in the name of growing feed and poor organic matter waste management, are not sustainable.
As the global population grows and available area of farmland decreases, novel solutions will be required to meet the demand for animal products while maintaining our environment. Black soldier fly farming, among other kinds of insect farming, offers hope, and viable solutions to these key issues – as a replacement animal feed that doesn’t require deforestation, and as a hyper-efficient waste management machine.
What is a Black Soldier Fly?
The black soldier fly, or Hermetia illucens, is a common and widespread fly of the family Stratiomyidae. It is just over 2cm long, and indigenous to tropical and subtropical regions of the Western hemisphere, and Australia.
Black soldier flies are not pests like regular house flies. On the contrary, they are actually very useful to humans due to their unique properties as decomposers. They are a necessary part of any ecosystem, aiding in controlling other insect pests, acting as pollinators, recyclers, and scavengers. Black soldier flies specifically are considered to be sanitary, non-pests. They are weak fliers and are typically seen resting on nearby structures or vegetation.
Their lifecycle is peculiar, with female adult black soldier flies laying their eggs not long before dying. Those eggs hatch into larvae, which will then mature into flies, and the process starts again.
These flies are beneficial to the agricultural industry because of their role in manure and waste management. They are designed to break down the bacteria in their food. In fact, black soldier flies are so good at this decomposition, that there is no waste in their byproducts once they’ve digested their food.
What is Black Soldier Fly Farming?
Black soldier fly insect farming is the process of raising black soldier flies for consumption. The most common application of these farmed flies is as animal feed for livestock.
At the larval stage, these insects are packed with nutrients, as they consume as much as possible before entering the fly stage of their life cycle. Black soldier fly larvae are a great source of protein, containing up to 43% protein by weight, as well as other significant micronutrients such as calcium.
Beyond their application as animal feed, these flies are also excellent decomposers, which makes them the ideal candidate for processing compost and other organic waste materials into inert substances. This basically means the black soldier flies can be raised into valuable animal feed on low-input systems of food scraps and a low budget set up.
This low-input high-output model has sparked interest in the entrepreneurial world, with several companies starting commercial black soldier fly farms for industry. Examples include Entocycle in the UK and Enterra in Canada.
How Do These Farms Work?
Setting up a successful black soldier fly farming operation does not require any fancy equipment or a lot of space. Here are some factors to consider and steps to take.
Choosing a location for optimal conditions
Black soldier flies are sensitive to light, heat and humidity. All of these factors must be considered when selecting where the cage will be placed. The mature flies only mate under certain light conditions, so it is recommended to allow as much direct sunlight to hit the cage as possible for successful mating. If farming indoors, under a window is optimal.
Another factor that facilitates successful mating is warm temperatures. Ideally, the cage temperature should not fall below 23C leading up to mating, and should remain above 13C for the colony’s survival. Similarly, black soldier flies thrive at 50% humidity, so be sure to maintain air moisture appropriately.
Setting up the cage
Once the location has been selected, it is time to set up the cage and habitat for the black soldier fly farm. The cage itself can be made either of PVC pipes and covered with baby insect-proof netting, or built from wood-framed screens covered in mesh. The cage dimensions can range depending on the size of the farming operation, but 48 x 25 x 20 inches is a good starting point.
Inside the cage, there needs to be a clean water source. A small fountain can be created by filling a simple, shallow disc with water from a hose. Ensure the disc isn’t too deep or the flies will drown.
Additionally, the black soldier flies require a food source, and an attractant for oviposition, or egg-laying. The food source is a box of rotting organic matter such as food scraps, grass, or coffee grinds. Ensure the substrate is kept moist, and isn’t more than 3 inches deep, as this will cause problems for the larvae when they start burrowing in later in their growth.
If left unattended, the food box will need changing every 2 to 3 days to prevent molding. A workaround to this is to add one or two thousand larvae into the organic matter. They will eat the mold-causing fungus and release chemicals that prevent that fungus from forming in the first place. This means the substrate can be replaced much less frequently.
For oviposition, 4 to 5 pieces of flute-shaped cardboard is needed. Secure them together with rubber bands and place them directly above the food source. This is where the females will lay their eggs once mating has terminated.
Harvesting eggs and hatching
The cardboard flutes will fill with eggs. Every 1-2 days, empty the flutes and place the eggs in the food box of organic matter along with the larvae that are keeping it from molding (replace the cardboard for new eggs). Black soldier fly larvae are not cannibalistic as some other insects like crickets are. They will not feed on the newly-added eggs, unless the eggs are already dead and rotting.
If eggs are hatching in low numbers, this egg failure is likely due to either low humidity plus high temperature. This typically occurs in small rooms where the heater is turned on. Try adjusting one or both of these factors and see if hatching rates improve.
If there is no improvement, it could be that some eggs are simply unfertilised. Unfertilised eggs are sometimes developed by the female regardless of mating. If a mating pair is interrupted before they finish, then these developed eggs will sometimes be laid even though they are unfertilised. In this case, reducing human activities or improving the light source could help boost hatching rates.
Under temperatures of 27 – 30oC, the larvae reach visible size 10 days after hatching and are ready to start breaking down the organic matter in the food box.
Ensure the substrate is no more than 3 inches thick. Larvae start burrowing down, and they don’t stop. If the substrate is too thick, the larvae risk being unable to return to the top of the pile and dying from overheating or lack of oxygen. Secondly, the fresh food added to the surface will sink to the bottom due to the wiggling motion of the larvae. If the substrate is too deep, no more food will be available for the larvae if it all sinks down too far.
The larval population will thrive as long as the substrate has good ventilation and the temperature remains below 44oC. Any hotter, and the colony will start dying in the substrate. To ensure proper ventilation is maintained, add some low density, high rigidity substances to the substrate to create some pore space for breathing. These substances include wheat bran, wood shaving dust, or rice bran, for example.
Black soldier flies are self-harvesting. This means as larvae, they have a compulsion to climb a ramp, which leads to a tube that leads them in turn to the harvesting bucket. It is imperative to ensure that enough larvae are harvested every cycle to make the operation worthwhile, yet also retain enough larvae and allow them to mature into flies to be able to continue the cycle.
Farming Black Soldier Flies: The Good and Bad
Benefits of black soldier fly insect farming
From trash to treasure
The most obvious benefit of farming black soldier fly larvae is they turn waste into a valuable input – their food source! Turning waste into something productive closes the loop in a farming system, and makes it more economically viable and environmentally friendly.
In the larval stage, these insects can eat twice their body weight per day, so can grow at a hugely accelerated rate. This means low cost and time from hatching to harvest – making it a very viable business model.
Black soldier fly larvae feed on literal waste products, and are very efficient at turning them into their own biomass. 1.5kg of decomposing organic matter creates 1kg of black soldier fly larvae, which in turn create 100g of beef, if used as feed for cattle. They are highly efficient energy conversion machines.
Black soldier flies, if used for human consumption, are highly environmentally friendly, as they don’t require any high-impact, destructive activities that traditional meats require, such as mass-scale deforestation, land use change, water inputs, and more. Lower emissions with the same high quality protein.
Drawbacks of black soldier fly insect farming
The biggest challenge facing black soldier fly insect farming is scaling up the operations to be able to seriously compete with traditional animal feed suppliers at an industrial level. The insect-for-feed industry as a whole has struggled to build infrastructure, breed sufficient quality ‘parent stock’, meet consistent standards of product, and combat restrictive legislation.
The predominant insect-for-feed product on the market currently is mealworm, which has enough popularity to make it well established. Thus, black soldier fly farming is still the underdog of the industry, despite having shorter life cycles than mealworms, making them the more economically viable insect to farm.
Another risk to commercial black soldier fly farming operations is that the traditional animal feed sector could decide to slash their prices and drive the little insect-for-feed businesses into the ground. Though if predictions are correct, the insect-for-feed sector will be worth $1 billion by 2022, representing a significant impact on the livestock farming industry.
Black soldier flies are powerhouse insects that can turn organic waste into high protein feed, without generating any waste byproducts. Farming these insects is a very low cost, low maintenance, highly efficient small-scale operation.
On a global scale, using this larvae as feed for livestock has the potential to drastically minimise the carbon emissions associated with animal agriculture, treat organic waste in a sanitary way, and provide a novel source of protein for human consumption.
ARTICLE BY PINDUODUO