Mexican Rice Borer - Eoreuma loftini (Dyar)

On the meso-and metathorax of the larva (right above the “prolegs”), the Mexican rice borer has only one seta (hair), while the rice stalk borer has two setae.

Ref: KEY TO SELECTED PYRALOIDEA (LEPIDOPTERA) LARVAE INTERCEPTED AT U. S. PORTS OF ENTRY: REVISION OF PYRALOIDEA IN “KEYS TO SOME FREQUENTLY INTERCEPTED LEPIDOPTEROUS LARVAE” BY WEISMAN, 1986, M. ALMA SOLIS.

Also, in general, the Mexican rice borer has light colored hairs and head capsule while the rice stalk borer has dark hairs and head capsule.