Naupactus argentatus is similar to N. cinereidorsum by the uniformly grey scaly vestiture, pale, short and recumbent setae; convex eye, broad antennae, well-developed, oblique humeri; small denticles on the inner margin of front tibiae and absence of corbels at the tip of hind tibiae.

Naupactus argentatus distinguishes from N. cinereidorsum mainly because the vestiture is iridescent (silver-colored); the pronotum is truncate-conical, with more straight and divergent sides, and the elytra are longer.

This species has caused damage to Saccharum officinarum L. (Poaceae) in northern Santa Fe. It is mainly associated with native vegetation of the gallery forests of the Paraná river.