The authors agree that this surname derives from the place name Erba, a locality of the province of Como, in Lombardy. E. De Felice describes it as a surname formed directly from that place name, with frequent presence in the Milan area. E. Rossoni specifies that it is specific to the Como area and to the north of the Milan area.

F. Miranda broadens this base and notes that the name of the locality of Erba could allude to the very green landscape that surrounds it. He adds that the surname, although concentrated mainly in Lombardy, presents small nuclei in other regions: Sicily, Piedmont, Lazio, Emilia-Romagna, Liguria, Campania and Sardinia.