BENEFITS OF BLACK SOLDIER FLIES
Black soldier flies (Hermetia illucens) are a species of fly native to the Americas but now found worldwide in warm and temperate regions. They are known for their larvae, which are highly efficient at decomposing organic waste, making them valuable in waste management and as a sustainable source of animal feed.
Adult black soldier flies look like black wasps, but they do not sting or bite. They have clear wings and distinctive dark stripes on their abdomen.
The life cycle of a black soldier fly consists of four stages: egg, larva, pupa, and adult. The larvae are the most important stage because they consume large amounts of organic material. They decompose organic matter as larvae and then pupate.
Black soldier fly larvae (BSFL) are efficient decomposers, breaking down organic waste like food scraps, manure, and agricultural byproducts. They reduce waste volume significantly and can convert waste into compost and valuable products like biofuels. Using BSFL in waste management helps reduce greenhouse gas emissions and landfill use. The frass (excrement) left behind by the larvae is a nutrient-rich fertilizer, promoting plant growth.
The larval and pupal stages are used as livestock and pet feed, turning waste into resources. They are rich in protein and fat, making them an excellent sustainable protein source for poultry, fish, livestock, and pets.
BLACK SOLDIER FLIES AS ANIMAL FEED
Larval Stage
BSF larvae are nutrient-rich, typically with around 40-45% protein and 30-35% fat, along with essential amino acids, vitamins, and minerals, making them excellent feed for a variety of animals, including poultry, fish, reptiles, and pets like birds and amphibians.
BSFL are easy to harvest and process. They are typically collected just before they enter the pupal stage when they have accumulated the most nutrients. The soft bodies of the larvae are easily digested by animals, making them a highly efficient feed option.
Pupal Stage
As BSF larvae transition into the pupal stage, they use some of their stored nutrients to fuel metamorphosis into adult flies. This can slightly reduce their overall nutritional value compared to larvae. As the pupae develop a harder exoskeleton, they become less digestible for some animals, particularly those that are not adapted to eating hard-shelled insects.
For these reasons, the pupae can still be used as animal feed, but they are generally less favored than larvae. However, some animals, particularly those that naturally consume insects with hard exoskeletons, like chickens, can still benefit from them.
Nutritional Value Depends on What You Feed Them
The nutrient content of BSFL is significantly influenced by their diet. What the larvae consume directly affects their protein, fat, and overall nutritional profile. In essence, they are what they eat.
If BSFL are fed protein-rich material, particularly meat products, they accumulate higher levels of protein. This makes them particularly valuable as a protein source in animal feed.
In this way, chicken meat can be fed to BSFL, which can then be fed to chickens, circumventing the dangers of feeding chicken meat directly to chickens. This gives farmers a way to recapture valuable protein when they lose a chicken and eliminates the need to dispose of carcasses.
On the other hand, feeding the larvae low-protein materials, such as plant matter, can result in lower protein levels in the larvae. When fed higher fiber materials, some of their digestive energy is used to process the fiber.
A diet high in fats or oils leads to an increase in the fat content of the larvae. This can be beneficial for animals that require more energy-dense feed, such as broilers. Larvae fed low-fat diets will have lower fat content, which might be preferred in some animal feeds where lower fat levels are desired.
The mineral content in the larvae, such as calcium, phosphorus, and magnesium, is also influenced by what they consume.
A balanced diet that includes a mix of protein, fats, carbohydrates, and essential minerals generally produces larvae with a more balanced nutritional profile, making them more versatile as animal feed. Specialized diets can be used to optimize the larvae for specific nutritional needs, producing larvae with desired protein, fat, or mineral levels.
The nutritional content of black soldier fly larvae is highly dependent on their diet. By adjusting what the larvae consume, it is possible to influence their protein, fat, and mineral levels, making them a customizable and versatile option for animal feed. This adaptability is one of the reasons BSFL are considered such a valuable source of feed.
HARVESTING BLACK SOLDIER FLIES
Active Self-Harvesting
As BSFL get ready to pupate, they naturally begin to migrate out of their feeding substrate in search of a suitable place to pupate. Systems can be designed to allow them to "self-harvest." For example, inclined ramps or channels can be set up in rearing bins, guiding the larvae to crawl out and drop into a collection container.
My favorite is to place the BSFL in a bucket (filled with Inoculated Deep Liter which keeps other flies out) and hang the bucket in the chicken coop. As the larvae get ready to pupate, they crawl out of the bucket and drop down to the hungry chickens below.
Aggregation and Density
BSFL tend to cluster together, especially as they near the end of their larval stage. This aggregation makes it easier to collect them en masse. While BSF larvae are active feeders, they are relatively slow-moving, making it easy to gather large quantities using simple tools like sieves, scoops, or mechanical separators. Larger and heavier than the fine particles of organic material they feed on, they can be easily separated by passing the material through a mesh or sieve.
Automated Systems are designed to continuously collect larvae as they naturally migrate from the substrate, reducing the need for manual labor and making the process more efficient. Simple gravity-based traps or ramps can be used, where larvae naturally fall into collection bins. This method is effective and low-cost, suitable for both small-scale and large-scale operations.
Harvest Timing
Larvae are typically harvested at the pre-pupal stage, just before they stop feeding and begin the transition to pupae. At this stage, they are at their largest and most nutrient-dense, making them ideal for collection. In the pupal stage, they are less mobile and often hidden within the substrate or in hard-to-reach places, making them more difficult to harvest. Adult (flying) BSF are not practical for feed purposes and are needed for reproduction.
KEEPING BLACK SOLDIER FLIES
Black soldier flies (BSF) can be kept in a variety of environments, but there are specific conditions that need to be met for them to thrive. They prefer warm temperatures, ideally between 24°C to 30°C (75°F to 86°F). They can survive in a range from 20°C to 40°C (68°F to 104°F), but their development slows outside their optimal range.
They thrive in moderate to high humidity, ideally with levels between 60% and 70%, especially for the larval stage. BSF prefer shaded areas and are not active in direct sunlight. They should be kept in a sheltered location that protects them from harsh weather. Good airflow is essential to prevent the buildup of harmful gases, especially in enclosed rearing systems.
BSFL need a consistent supply of organic waste, such as food scraps, manure, or compostable materials. This substrate should be moist but not waterlogged. The area where they are kept should have proper drainage to prevent excess moisture, which can lead to mold or other issues.
I find keeping the container stocked with bedding from the Inoculated Deep Litter System controls moisture perfectly. However, size is important. Very large containers are difficult to keep because it gets increasingly difficult to control moisture levels with living BSFL as the size of the container increases.
BSFL are typically kept in specially designed bins or containers that allow for the easy collection of larvae and frass (larvae excrement). These enclosures should prevent the escape of larvae while allowing adults to emerge and mate. Of course, if they are kept with chickens or pigs, the runaways will become feed automatically. Expensive containers are not needed. A simple bucket can work just fine. In homemade systems most people try to install something to allow the larva to crawl out to pupate, but I have found this not to be necessary.
Enclosures should be designed to minimize access from pests like rodents, ants, or other insects that might compete with or harm the BSF. Hanging a bucket and covering organic matter with inoculated animal bedding does all these things.
KEEPING BLACK SOLDIER FLIES IN COLD PLACES
BSF can be kept in many places, including urban, suburban, and rural settings, as long as the environment is warm, humid, and provides adequate shelter and food. But what if you live in a place that gets cold and freezes?
INDOORS
In colder climates, BSFL are often kept indoors in temperature-controlled environments, such as greenhouses, heated barns, or dedicated insect-rearing rooms. This ensures that the larvae and adults remain within their optimal temperature range (24°C to 30°C or 75°F to 86°F). Some setups use insulated structures to maintain warmth during colder months. These structures might include heating elements or rely on passive solar heating.
SEASONAL
Overwintering: In regions with cold winters, BSF may not survive outdoors, so it's common to only rear them during the warmer months. The larvae can be collected and dried or frozen for use throughout the year. Alternatively, some farmers will collect eggs or larvae at the end of the warm season and keep them in a controlled environment over winter.
Breeding Cycles: Some growers synchronize the breeding cycle with the warmer months, allowing adults to emerge and mate during the optimal time of year.
ARTIFICIAL LIGHTING
BSF adults require specific light conditions for mating. In colder, darker months, artificial lighting that mimics natural sunlight and photoperiods can be used to encourage mating and ensure a continuous life cycle.
SUPPLEMENTAL HEATING
In small-scale setups, heating mats or infrared lamps can be used to maintain the necessary warmth for larvae. This is particularly useful for indoor bins or smaller containers.
MOBILE HOUSING
Some farmers use portable structures that can be moved indoors during the winter and outdoors during the summer. These units are designed to protect the flies from cold temperatures while allowing them access to organic waste.
HIBERNATION AND DORMANCY
BSF larvae can enter a state of reduced activity in response to lower temperatures. While they won't be as productive, they can survive in this dormant state if temperatures do not drop too low (generally not below 10°C or 50°F).
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