Oyster mushroom (Pleurotus ostreatus), is an understudied area of agriculture. The fungus gnat in the genus Lycoriella spp. is the most damaging pest found on mushroom farms. Chemical pesticide applications can damage the crop itself as well as cause less marketability. Biopesticides have yet to be assessed in this system. However, in the Agaricus white button mushroom BacillusÂ thuringiensis israelensisÂ (Bti) and entomopathogenic nematodes have been found to effectively control fungus gnats. This study used a randomized complete block design to compare biopesticide treatments along with a control. The entomopathogenic nematode treatment was not significantly different than the control, however the Bti treatment produced statistically significantly fewer fungus gnats than the control and visually fewer than the nematode treatment. This study provides the first insight into managing fungus gnats in an oyster mushroom system.