The adult beetle is reddish brown to black in colour measuring 17 x 6 mm (Fig 109). The life cycle occupies 3-5days for eggs,20-26 for grubs and 20-25 for pupae during summer and slightly longer for winter. Adult weevil keeps their eggs in air chamber through slits cut on leaf sheath. Mating occurs in the mating spaces especially encarved by adults while feeding between leaf sheaths. Frequent mating is observed. Preovipositin period is 15-30 days. Adults mate throughout the day and night. Female makes small slit with rostrum on the outer epidermal layer of leaf sheath down up to air chamber and insert ovipositor to lay a single egg –one egg in one air chamber.There are 5 larval instars . Full grown grub measures 16-20 mm.
Immediately after emergence the neonate larvae start feeding on the tissues around the air chamber of leaf sheaths, while the feeding larvae move across horizontal or in a slight oblique direction and bores in to inner leaf sheath. Third, fourth and fifth instars are voracious feeders and riddle the pseudostem by cutting holes. Sometimes the grubs also make holes on the outer surface, for better aeration of the tunnels and thus cause heavy damage.Pupation takes place inside adjoining leaf sheath of pseudostems in a cocoon formed by plant fibres. The cocoon is formed by winding short pieces of fibrous materials of sheath around the body.
In Kerala total life cycle of the weevil takes about 42 days and adult longevity is 90 -120 days.