Banana root borer

Cosmopolites sordidus

Common name:

Banana root borer

Scientific name:

Cosmopolites sordidus

Alternative common names:

Banana weevil borer, banana root weevil, banana rhizome weevil, banana borer, plantain weevil, corm weevil, banana beetle. 

The banana root borer is a major pest of the banana plant and infests all types of bananas. The insect originated in Southeast Asia and has spread to all the important banana and plantain plantations in the world. It is not usually a pest in its area of origin.

Additional Info

  • Where does this species come from?

    Southeast Asia.

    What is its invasive status in South Africa?

    NEMBA Category 1b.

    Where in South Africa is it a problem?

    KwaZulu-Natal.

    How does it spread?

    Via transportation of infested planting material.

    Why is it a problem?

    It causes root damage, reduced growth, decreased fruit production, and it can sometimes cause plants to topple over.

    What does it look like?

    Description: Adults are 10-16mm long weevils (snout beetles), and are hard-shelled with a long, curved snout. Newly emerged weevils are red-brown, turning almost black after a few days. They often remain within the plant for some time before biting the external sheath and leaving the banana plant. They feed on dead banana plants, newly cut stems and other decaying plant material near the base of banana plants. These weevils can live for up to two years, and can live without food for six months, but are sensitive to desiccation and will die within 48 hours if kept in a dry substrate. They are active at night. The adults are sluggish and rarely fly, but commonly walk over the soil surface and vegetation and feign death when disturbed. Habitat: Found under debris or in the soil around banana plants. They are most commonly found between leaf sheaths, in the soil at the base of the mat or associated with crop residues. Breeding: Eggs are laid between leaf sheaths and stems as well as around the corm, often in the enlarged, cell-like compartments in the tissue. They are usually deposited singly, with the newly hatched larvae boring into the corm. The complete life cycle is from 30 to 40 days, with the egg stage five to seven days, larva 15 to 20 days and pupa six to eight days.