Banana Weevil Borer

Banana Weevil Borer (Cosmopolites sordidus) adults are about 10-12mm long, hard shelled and have the pronounced snout typical of weevils. The newly emerged weevil is reddish brown but soon becomes uniformly dull black. The weevils are nocturnal and hide during the day in or around corms or in moist areas near the plant and in the trash. Unusually sluggish in their movements, they feign death when disturbed and seldom fly. Natural spread is very slow. Dispersal is primarily by the introduction of infested suckers and bits for planting. The larvae tunnel within the corm that lies below the soil surface. When there are large populations, tunnels are found through most of the corm tissue and a short distance up the pseudostem. This tunnelling weakens the plant and renders it susceptible to ‘blowdown’ in windy weather. Heavy infestations interfere with the movement of nutrients to the plant, and plants appear unthrifty. In severe cases the young suckers whither and fail to develop.