Fauna: Black Soldier Flies & Larva

Hermetia Illucens

A.K.A. – BSF, BSFL, Phoenix Worms, Calciworms, Nutrigrubs

Native to: Central and South America, but now established on nearly every continent.

Environment: Flies and larva prefer warm, tropical climates. Warm, humid conditions and adequate lighting are required for mating.

Eats: Larva eat decomposing plant and animal matter (compost). Bee pollen and/or small amounts sugar water can be offered as food for adult flies, who would dine on nectar in the wild.

Sexing: Female flies have a scissor shaped tip on the end of their abdomen, males have a more blunted tip.

Life Cycle:  Eggs are laid in cracks and crevices near a food source, and sometimes directly on the food source. Eggs hatch after approximately 4 days. Larva emerge from eggs and grow for approximately 4 weeks while gorging on food. When larva turn black in color they will begin to look for a safe place to pupate. Larva then turns dry and hard as it remains in the pupal stage for 1-2 weeks in optimal conditions – in some instances pupation can take several weeks or even months. Flies then emerge to mate and repeat the cycle.

Eggs: Eggs are typically laid in cracks and crevices near or directly above a food source. A single female can lay 200-600 eggs at one time.

Nutritional Information: Larva are considered an excellent feeder that is very high in calcium. Darker larva have the highest calcium levels. Nutritional information is not available for flies. Nutritional information below is for larva, only, and gathered from DubiaRoaches.com.

Moisture: 61.2%

Protein: 17.5%

Fat: 14%

Fiber: 3%

Calcium: 9340mg

Phosphorus: 3560mg


Care Recommendations:  If caring for grubs, for purpose of feeding, only, keep them cool and in a dark room or container to slow pupation. Larva should be kept in slightly moist, but not wet substrate. Larva will readily eat any food scrap, but foods with protein are preferred over leafy greens. A prepared insect chow such as Repashy Bug Burger or Arcadia Insect Fuel is recommended for protein, at least as an occasional meal, rather than offering animal protein.

Larva are high in calcium and low in phosphorus, so they do not need to be dusted with calcium supplements. Your animal will likely appreciate that! Some keepers like to dust with bee pollen, to do so – slightly moisten the larva and then sprinkle them with bee pollen as a healthy nutrient supplement.

Larva can occasionally pass through the GI tract without being digested, sometimes emerging from stool still wiggling! Puncturing the larva with a pin point will aid in digestion, but is not required.

To feed flies, larva can simply be tossed into the soil of a live plant to pupate. Metamorphosis takes several weeks. Larva can also be placed into a plastic container with a small hole punched, or an empty, plastic gum container. Flies will crawl out once they emerge from pupal case.

Breeding black solider flies requires adequate sources of light (sunlight or  similar light spectrum) and a source of humidity. A small compost bin should be placed in a screen enclosure with the flies, with moist smelly compost. Flies will lay eggs directly on the compost if a suitable alternative is not available. It is recommended to place several small pieces of card board or corrugated plastic sheet, tied together as a bundle, directly above the compost pile. Cardboard can be hung or placed on a barrier, such as Gutter Guard. Flies will lay eggs in the crevices of the corrugated material, which can then be emptied into a hatching/rearing bin, of left to hatch and fall directly into the compost below.

Finally, Black Soldier Fly Larva make excellent composters, and as such, have become a popular insect for farmers and gardeners to raise. The larva tunnel through the soil, turning and aerating it as they go. Their frass (poop) also creates a partially composted fertilizer and soil additive. When naturally mixed into the soil, and working with other clean up crew, Black Soldier Fly Larva can also be beneficial to your plants. They’ll also work with your clean up crew to break down animal waste and decomposing plant materials, eventually turning into flies which either feed your animal, or simply mate and add more larva in the soil.



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