The first occurrence of Oecetis testacea was at Magyarszombatfa (West-Hungary) in 1983. It was repeatedly found also at Magyarszombatfa in 1985. No further specimens of the species have been collected at the same locality since
then. However, in 1996 and 1998 it was again collected by light trapping, in considerable numbers, at Bernecebaráti (Börzsöny Mountains, Northern-Hungary)
