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Plantwise Factsheets for Farmers

Managing Banana Corm Weevils with Pseudostem Traps

Cosmopolites sordidus

Recognize the problem

The banana corm weevil is a black beetle (1-1.5 cm long), which is found in debris around banana plants. Female beetles lay eggs singly in small cavities at the base of the pseudostem of the plant.  Larvae hatching from the eggs are stout and creamy white, legless grubs which are distinctly curved and swollen in the middle. The head is reddish-brown with strong mouthparts. Fully-grown grubs are about 12 mm long. The larvae bore irregular tunnels in the rhizome/corm. Heavy infestation kills young plants. Heavily infested older plants are easily blown over by wind.


The pseudostem trap is simply a fresh 20 – 60 cm longitudinally halved piece of a banana pseudostem  placed on the ground near a banana mat with its inner side facing the ground. It traps banana corm weevils in a way that if adult banana weevils are around, they are attracted to its underside for shelter and egg-laying. However, such a piece of banana pseudostem can easily be turned over to expose the hiding beetles so that they are killed mechanically. Also, the eggs which they lay there cannot complete development to adults since the pseudostem piece is small and dries in a short time.


Pseudostem traps can be used for monitoring and managing populations of corm weevils in banana fields.  

For monitoring, set 20 traps per hectare and check them weekly for hiding beetles. If the population / catch gets to an average of 1 or more beetles per trap per week, control measures should be employed.  

For control (mass-trapping), set 100 traps per hectare and check them weekly for hiding beetles and kill them mechanically if found, e.g. by crushing them with a stone. Replace the traps when they are dry.

The recommendations in this factsheet are relevant to: Malawi

Authors: Donald Kachigamba
Bvumbwe Agricultural Research Station
tel: +265(0)996384072 email:
©CAB International. Published under a CC-BY-SA 4.0 licence.

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