He was the son of the Count of Ellwangen, and related to Gozbald, archchaplain and chancellor to Louis the German.

[2] Herulph and his brother Erlolf became Benedictine monks of the Abbey of St. Gall in Switzerland.

Sulpicius and Servilian, which he had obtained from Pope Adrian I, and they became the main patron saints of the first monastic church.

Erlolf died in 785 and was buried in the monastery church of St Vitus at Ellwangen.

A Vita Hariolfi was written by the Benedictine monk, Ermanrich of Passau.