The black soldier fly
— Hermetia illucens.
One of the most efficient organisms in the natural world. Every Calci Worm we sell and every bag of Flytiliser we pack comes from this remarkable insect.
See our farm →How the black soldier fly lives and what makes it special
The black soldier fly (Hermetia illucens) is a member of the order Diptera — the same order as houseflies. But that is where the similarity ends. The BSF is a remarkably benign insect: the adult does not eat, does not bite, and has no interest in human food or waste. Its entire adult life — just 5–8 days — is devoted to mating and laying eggs. It then dies.
All the nutritional action happens in the larval stage, which lasts 14–18 days under optimal conditions. During this time, the larvae are extraordinary bioconverters — capable of consuming and reducing organic material by 50–70% of its original volume while converting a significant fraction into protein, fat and other valuable compounds. This is what makes them the basis of a genuinely circular operation.
The four stages
Egg (3–4 days)
Females lay clusters of 500–900 eggs in crevices near organic material. Eggs are tiny, cream-coloured, and hatch in 3–4 days at optimal temperature (27–30°C).
Larva (14–18 days) — this is what we sell
The larval stage is the nutritionally dense phase. Larvae progress through six instars (growth stages), consuming organic substrate continuously and growing rapidly. At harvest, late-instar larvae are 14–20mm and packed with protein, fat and calcium. This is the Calci Worm.
Pupa (7–14 days)
Pre-pupae stop feeding and actively seek a dark, dry place to pupate. The pupal case darkens and hardens over 7–14 days as the adult form develops within. A proportion of each batch is allowed to complete this cycle to maintain our colony.
Adult fly (5–8 days)
Adult black soldier flies do not eat or drink. They are entirely harmless — non-biting, non-food-seeking, and incapable of transmitting disease. They mate, the females lay eggs, and the cycle continues. Our colony is entirely self-sustaining.
Why BSF and not another insect?
Of all the insects used in farming, black soldier fly larvae occupy a uniquely productive niche. Their feed conversion efficiency exceeds that of crickets, mealworms and most other commercially farmed insects. They can process a wider range of organic inputs than most species, including food waste streams that would be unsuitable for other insects. And they produce two distinct valuable outputs — protein and frass — from a single farming system.
Their calcium content — approximately 37 times higher than mealworms on a comparable fresh-weight basis — is a function of how larvae concentrate minerals during their rapid growth phase. It is the defining characteristic of Calci Worms and the reason they are the preferred live food for calcium-dependent animals like laying hens and insectivorous reptiles.