Fungus gnats, which are also commonly known as mushroom fly, nuisance flies, black fungus gnats, and dark-winged fungus gnats, are small, dark-coloured flies that belong to the family Sciaridae. Although fungus gnats are principally mycophagous, they have also been described as opportunistic herbivores, making them important plant pests. They are primarily a problem in high moisture conditions. They cause direct damage on the plant through larval feeding and indirect damage through creation of entry points for plant pathogens. They also transfer fungal diseases between plants. The most important species that have been described as pests are Bradysia coprophila Lintner and Bradysia impatiens Johannsen. The latter is regarded as synonymous to Bradysia difformis, has a global distribution and has recently been identified in South African forest pine nursery beds. Control has mainly been achieved through the use of chemical insecticides, but also, to a considerable extent, the use of biocontrol agents such as entomopathogenic nematodes (EPNs). The use of EPNs is preferred, since fungus gnats are pests of such crops as mushrooms and vegetables that have a short lifecycle, or of houseplants that are in very close association with human beings. Control usingEPNshas mainly been achieved through the use of Steinernema feltiae.