Naupactus argentinensis is a large species, densely covered with small ash-grey scales and short recumbent setae. Antennae are broad, pronotum is truncate-conical, with strongly curved flanks, convex disc, deep midline sulcus, and bisinuate beveled base; elytra have strongly bisinuate base, broad humeri, uneven intervals 3°, 5° and 7° more convex the even intervals; front tibiae bear large denticles on inner margin and corbels of hind tibiae are broad, squamose. Males are unknown.
Naupactus argentinensis causes damage to Gossypium hirsutum L. (Malvaceae) (Lanteri et al. 2002a).
It is mainly associated with native vegetation of the Chacoan biogeographic province.