To Buy or DIY: Analyzing Methods of Rearing Black Soldier Flies

• Ryplee Davis, Insect Ecology and Conservation, University of Delaware

• Michael Crossley, Department of Entomology and Wildlife Ecology, University of Delaware

In the United States, approximately 30% of food produced is discarded, accounting for nearly 20% of municipal solid waste in landfills. One sustainable alternative is insect-based waste upcycling using black soldier fly larvae (BSFL), which convert organic waste into valuable products such as livestock feed and nutrient-rich soil amendments. While most BSFL research has been conducted indoors at a small scale under controlled conditions, less is known about effective rearing practices in outdoor production systems. This study evaluated the effects of diet and rearing bin design on BSFL yield at a large outdoor research site. Eighteen rearing bins were assigned to three diet treatments, grain, produce and grain, or meat and grain. The larvae were fed using spent grains from a local brewery while produce and meat were sourced from a local restaurant. Half of the bins were constructed from hardware store materials following published methods, while the remaining half were commercially manufactured BSFL rearing bins. Substrate conditions were monitored daily using a soil probe and an automated soil conditions monitor. Larval growth was assessed by periodically collecting and weighing subsamples, and final yield was determined by harvesting and weighing the prepupae. Commercial rearing bins produced the highest overall yields, while the produce diet resulted in the greatest larval growth and yield across both commercial and DIY bin designs. Because outdoor BSFL waste upcycling systems are relatively understudied, the findings from this research provide practical guidance for future experiments and the development of larger-scale waste upcycling operations.