The full-grown larval stage of Curculio mexicanus Gibson is described and illustrated for the first time. The larvae were collected in fruits (acorns) of several species of Quercus L. (Fagaceae): Q. pinnativenulosa C. H. Mull, Q. xalapensis Bonpl., Q. germana Schltdl. & Cham., Q. candicans Née and Q. polymorpha Schltdl. & Cham; all species with wide distribution in the Sierra Madre Oriental and representative of the mountain mesophilic forest of Xalapa, Veracruz, Mexico. The record of Curculio mexicanus in Veracruz constitutes the first report for this species, as previously it was only known in Chiapas, Durango, Guerrero, Nayarit, Oaxaca and Sonora, in Quercus magnoliifolia Née (Q. macrophylla Née). Of those five mentioned host species of Quercus: Q. xalapensis and Q. germana are listed as vulnerable; thus, it is important to carry out research concerning this interaction in order to develop conservation strategies for these oaks as well as correct management and control of the weevils.