Adult : 10-14mm long (when at rest), wing span 20-24mm, grey-black forewings with dark transverse lines and outer band pale and wavy ( E. cautella), outer band pale and bordered on both sides with dark lines (E. elutella). Larvae : caterpillar-like, 15-20mm, white, or pinkish/greenish, with brown head , with clearly defined forelegs, pro-legs and setae (hairs).

Eggs (up to 200 per female) are laid on the surface of food material or dropped between sack fibres. Larvae spin cocoons and the brown, spindle-shaped pupa is about 9 mm long. Entire life cycle is completed in about 25 days, depending on conditions. Adult life span is usually about 14 days.

Adults do not feed and have a typical circular flight during dawn and dusk. The larvae or caterpillars feed on flour, bran, whole meal, flakes, grain, nuts, etc. and are serious pests in flour mills where their webbing often clogs machinery, sometimes causing shutdown.