Adult : small, dull reddish-brown, 2.5-3.5mm long, good flier (S. oryzae); 3-4.8mm, shining reddish-brown to black, flight-less (S. granarius). Larvae : legless, creamy-white with brownish-black head, hump-backed, (S. oryzae); legless, white with dark head, hump-backed (S. granarius).

Eggs laid on grain surface. Larvae bore into grain and emerge as adults. Life span of adult is up to 5 months (S. oryzae), up to 9 months (S. granarius).

At first glance, both beetles look similar (adults as well as larvae). They can be distinguished by the four faint-reddish to pale yellow marks on the wing-case on S. oryzae which is absent on S. granarius. They are internal feeders (larvae feed inside the grain) and attack all kinds of grain and grain products, though S. oryzae is more prolific.