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Black Soldier Fly Larvae Reduced Dry Canada Goose Feces by 56%

Canada goose family with goslings on a shoreline in Ontario
Research · Other research

Researchers in Canada tested whether black soldier fly (Hermetia illucens) larvae could convert feces from Canada goose (Branta canadensis) into insect biomass and fertilizer. In laboratory trials, the larvae survived and completed their development even when fed a diet consisting entirely of goose feces.

The study, published online in the Journal of Environmental Management on 19 February 2026, began with field surveys of urban green spaces in southern Quebec and Ontario. Larger goose flocks were associated with more fresh droppings, illustrating how locally abundant geese can create concentrated fecal loads in parks and other public areas.

Canada geese at Parliament Hill and the relationship between goose numbers and droppings
Canada geese at Parliament Hill in Ottawa and the relationship between flock size and fresh droppings across the field sites. Figure 2 from López-Manzano et al. (2026), Journal of Environmental Management, CC BY 4.0. Source.

Larvae consumed more than half of the dry waste

In the laboratory, researchers compared diets containing no goose feces, a 50:50 mixture of goose feces and a standard rearing diet, and a diet made entirely from goose feces. In the untreated feces-only diet, the larvae consumed 56% of the dry fecal material over their development.

The larvae nevertheless performed less well on pure goose feces than on the standard diet. Survival in the untreated feces-only treatment was 80.6%, compared with 96.4% in the control and 95.4% in the mixed diet. Flies raised only on goose feces also developed more slowly, reached lower adult body mass and had shorter adult lifespans.

The 50% mixture produced a more favourable balance between waste reduction and insect performance. The researchers also found that autoclaving the feces reduced consumption in the feces-based diets and reduced larval growth in the pure-feces treatment.

Black soldier fly larval growth, survival, consumption and waste reduction across Canada goose feces diets
Larval growth, survival, substrate consumption and waste reduction across diets containing different proportions of Canada goose feces. Figure 3 from López-Manzano et al. (2026), Journal of Environmental Management, CC BY 4.0. Source.

Frass also supported plant growth

The material left behind after the larvae had fed, known as frass, was then tested as a fertilizer for duckweed (Lemna minor). At a concentration of 10 grams per litre, goose-derived frass increased duckweed yield by 32% compared with the standard Hoagland nutrient medium used as a control. The response was not simply greater growth in every trait: roots in the frass treatments were shorter, by as much as 83% at high concentrations. The authors interpret this as consistent with duckweed reducing root investment when nutrients are readily available.

Duckweed growth in fresh Canada goose feces and black soldier fly frass treatments
Duckweed growth in fresh goose-feces and black-soldier-fly-frass treatments, including the shorter roots measured under high-frass conditions. Figure 5 from López-Manzano et al. (2026), Journal of Environmental Management, CC BY 4.0. Source.

These results show that nutrients in goose feces can pass through an insect-based conversion system into both insect biomass and a fertilizer product. The authors describe this as a potential circular approach to handling wildlife-derived fecal waste in places where large goose concentrations create sanitation and nutrient-management problems.

Further work on safety, biosecurity and scaling is needed before the system could be applied beyond laboratory trials.

Sources and image credit

  1. López-Manzano, C., Mahdjoub, H., Arce-Valdés, L. R., & Khelifa, R. (2026). Using an insect for sustainable waste management of a superabundant bird. Journal of Environmental Management, 402, 128919. https://doi.org/10.1016/j.jenvman.2026.128919Primary peer-reviewed open-access article available online 19 February 2026 under CC BY 4.0. Field surveys covered 11 urban sites in southern Quebec and Ontario; laboratory experiments tested black soldier fly development and waste reduction on Canada goose feces, followed by a duckweed fertilization experiment.

Image: Fabian Roudra Baroi — Canada goose (Branta canadensis) family in Huntsville, Ontario, Canada, 4 June 2023; representative species image, not geese from the study. Source: Wikimedia Commons. · CC BY-SA 4.0 — https://creativecommons.org/licenses/by-sa/4.0/ · Source

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