Naupactus rugosus shows characters typical of weevils from dry environments. The integument is strongly sclerotized, black and nude of scales, except those which cover the scutellum, the base of pronotum and the elytral suture. Setae on the elytra are fine, white, long and erect. The antennae are broad, the eyes convex, the sides of the pronotum are strongly curved and the disc strongly rugose (with confluent granulation and irregular sulci); humeri are reduced, punctures of the elytral striae are large and intervals have transversal striations; front tibiae have large denticles on the inner margin; and corbels of the hind tibiae are absent.
Eggs and oviposition habits have been described by Marvaldi (1999) and first instar larva, by Marvaldi (1998).
Eupatorium sp, Senecio subulatus D. Don ex Hook. & Arn. and Grindelia chiloensis (Cornel) Cabrera (Asteraceae); Larrea divaricata Cav. and Larrea nitida Cav. (Zygophyllaceae) (Lanteri et al. 2002a).
It is mainly associated with typical vegetation of Espinal and Monte biogeographic provinces.