Horisme tersata, the fern, is a moth of the family Geometridae. The species was first described by Michael Denis and Ignaz Schiffermüller in 1775 and it can be found in the Palearctic realm.
The wingspan is 31–36 mm. The length of the forewings is 14–18 mm. The moths fly in one or two generations from May to August.
The larvae feed on Clematis vitalba.