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Plantwise Factsheets for Farmers

Pseudo stem traps for Banana weevils

Cosmopolites sordidus
Sri Lanka

Recognize the problem

Banana weevils are a major constraint for banana cultivation. There are two types of banana weevils which cause damage to the pseudo stem (stem weevils) and corm (corm or Rhizome weevils).
Larvae bore into the plant and feed on the stem and corm tissues, making tunnels. As a result of this damage, plants show growth retardation with yellowing of mature leaves. The infested plants tend to topple over at the soil level and lodging occurs at the point of pseudo stem damage. Tunnels and different life stages of weevil can be observed in both the rhizome and pseudo stems.


Black corm weevils are about 10-14 mm long and are found on the rhizomes and on the stem near the base of the plant. The reddish brown stem weevils are about 18-20 mm long and lay eggs only on pseudo stems.
Emerged adults can crawl or fly short distances in the plantation and tend to be attracted to the secretions/ latex excreted by wounds and cut ends.


There are two types of traps.
Type 1 -
  • Use fresh pseudo stems from harvested plants
  • Split 2 foot long pieces of stem longitudinally into two halves
  • These pieces are placed at different locations in the field, placing the cut surface to the soil. 30 such traps are recommended for one acre.
  • Traps and the weevils inside them are destroyed by burning every two weeks. Place new traps if damage persists.
Type 2 – Stem trap with insecticide
  • Cut fresh pseudo stems into 6-10 cm slices
  • Spread 6g of Diazinon 5% G over the cut surface of a one slice, place several pebbles on top, then place another slice of the same size on top of that. The pebbles in-between the 2 slices will stop the direct touching of the pseudostem slices and allow weevils to enter. 25 traps /acre are recommended.
  • Adult weevils attracted to the traps die due to the effect of insecticide
  • Replace traps fortnightly until the weevils are under control For a better control introduce traps at early stages of plantation.

The recommendations in this factsheet are relevant to: Sri Lanka

Authors: W. A.R.T. Wikramaarachchi, M. T. Gunasena, Disna Rathnasinghe, Sakila Banu

©CAB International. Published under a CC-BY-SA 4.0 licence.

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