none Microplitis mediator (Haliday) a gregarious endoparasite was recorded for the first time from Agrotis segetum (Schiff) in Ankara, Turkey. The female parasites found their hosts by responding to the faeces of the caterpillars. An average, females laid 15.5 plus or minus 1.6 eggs in the bodies of their hosts. The newly laid eggs were elongated, oval in shape and 0.23 plus or minus 0.004 mm long and 0.07 mm wide. They hatched in 5, 4 and 3 days at 20 plus or minus 2 degree C, 25 plus or minus 2 degree C and 30 plus or minus 2 degree C respectively when maintained at 60-70% R.H. and 14 : 10 light : dark regime.