The clonal propagation of Eucalyptus in plastic tube containers with growing media substrate without direct contact of seedlings with soil floor in nurseries, changed the status of insects such as fungus gnats (Diptera: Sciaridae), especially the genus Bradysia. This study monitored populations of adults within a Eucalyptus spp. tree nursery in the municipality of Bom Despacho, Minas Gerais State, Brazil. Adult samples were collected monthly, during seven months with 58 yellow sticker card traps, including 21 in a mini garden, 16 in a greenhouse, and 21 in a shaded house. All individuals collected were identified as Bradysia difforrais Frey, 1948 (= Bradysia paupera Tuomikoski, 1960) (Diptera: Sciaridae). The population dynamics of B. difformis were not correlated with environmental variables (temperature and relative humidity), but varied between the three sectors of the nursery. This work is the first report associated with the population dynamics of B. difformis of nursery seedlings of Eucalyptus spp. in Brazil.