Japanese privet (Ligustrum japonicum) is widely planted as an ornamental and shade tree in Mexico. In 2017 we discovered lepidopterous larvae causing severe defoliation on ornamental privet in Saltillo, Mexico. It was preliminarily identified as Palpita sp. using external morphology. Larvae were reared to obtain adults that were identified as the four-spotted moth, P quadristigmalis Guenee (Lepidoptera: Crambidae) using morphology of the genitalia and COI sequences. A comparison with similar species is provided. Larvae of P quadristigmalis, are defoliators and leaf-folders of trees and shrubs, and among their main hosts are olives and privets (Oleaceae). This is the first confirmed report of P quadristigmalis causing economic damage in Mexico.