Naupactus inermis is a small species, with slightly sclerotized integument, and slender antennae and legs. It differentiates from other Naupactus because it does not have denticles on the inner margin of tibiae (in most species of this genus the front tibiae have a line of denticles of different sizes).
The typical morphotype is covered with dense scaly vestiture with a characteristic brown and white pattern on elytra, intercalated with short, dark, erect setae, slightly longer towards apex. In the paraguayanus morphotype (paraguayanus variety sensu Hustache) the integument is almost nude of scales, except for two yellowish stripes along sides of pronotum, extended on the anterior quarter of 4º elytral interval, and another yellow stripe extended from the apex of rostrum to the apex of elytra. Males are more slender than females.
First instar larvae was described by Marvaldi & Loiácono (1994) under the name Mimographus ocellatus Lanteri.
Prunus persica L. (Rosaceae).
Associated with vegetation native to the Paranaense forest.