Pantomorus postfasciatus has been frequently misidentified as Naupactus ambiguus Boheman (Lanteri et al. 2002a b; Guedes et al. 2005), which only occurs in Brazil.
It differentiates by the very prominent (but not conical) eyes; the slender and not squamose antennae; the very wide pronotum, with strongly curved flanks; and the globose elytra, covered with middle- length erect setae. The scaly vestiture is mostly pale brown, with a characteristic dark brown macula on the center of the pronotum, and three transversal dark brown stripes on the elytra (anterior, middle and posterior thirds), flanked by white scales.
Some populations are bisexual (with male and females in about similar proportions) and others are probably parthenogenetic. Females are frequently infected with the bacterium Wolbachia which induces parthenogenesis in several species of Naupactini (Rodriguero et al. 2010a). The first instar larva of P. postfasciatus was described by Marvaldi & Loiácono (1994).
Prosopis alba Grisebach (Fabaceae) in Santiago del Estero, Solanum viarium Dunal (= tropical apple) (Solanaceae) and Galega officinalis L. (Fabaceae). Solanum viarium is a perennial shrub naturally distributed in Argentina and Brazil, which has become invasive in other areas of South America, North and Central America, Africa and Australia. Galega officinalis is an herbaceous plant native of Europe and Asia.
In Argentina P. postfasciatus causes damage on Citrus sinensis (L.) Osbeck (Rutaceae), and minor damage on Medicago sativa L. (Fabaceae), Helianthus annuus L. (Asteraceae), Gossypium hirsutum L. (Malvaceae) (Lanteri 1994, Lanteri et al. 2002a), and Glycine max (L.) Merr. (Fabaceae). In Brazil (São Paulo and Minas Gerais) causes damage on Citrus spp (Lanteri et al. 2002b, Guedes et al. 2005).
It is mainly associated with vegetation of the gallery forests of Chaco and Cerrado biogeographic provinces.