Third-instar larvae of Phyllophaga (s.str.) ilhuicaminai Morón and Phyllophaga (Listrochelus) cuicateca Morón and Aragón are described. Larvae of P. ilhuicaminai were taken only from the roots of Limonium sinuatum (L.) Miller (Plumbaginaceae), an ornamental herb growing in fields near Atlixco, Puebla, Mexico. Larvae of P. cuicateca were found only on roots of Amaranthus hypocondriacus L. (Amaranthaceae) in fields near Altepexi, Puebla, Mexico. These larvae cause damage to the root system of both plant species under culture. Illustrations of diagnostic structures, a brief discussion on the differences between these larvae and other Phyllophaga Harris larvae, and a key to the Mexican larvae of the genus are included.