Black soldier flies, Hermetia illucens (L.) (Diptera: Stratiomyidae) are of particular interest for their application in waste management such as reducing manure accumulations in confined feeding operations. Determining black soldier fly development time as a result of climatic variations will allow for optimizing their utilization as a waste management agent at landfill sites and confined animal feeding operations. To implement a black soldier fly waste management program in Canada, where seasonal variability does not support H. illucens development on a year round basis, determining maximum and minimum abiotic thresholds to sustain larval development is important. In Canadian winters, maintaining greenhouse temperatures necessary for black soldier fly development results in low relative humidity that could impact their development. The objective of this study was to determine relative humidity thresholds on egg eclosion and adult emergence. Egg eclosion success was measured at 25, 40, 50, 60, and 70% relative humidities and adult emergence success was measured at 25, 40, and 70% RH. Egg eclosion and adult emergence success increased with increasing relative humidities, while development time decreased with rising relative humidities.