Divisi
Banana weevil
Cosmopolites sordidus · Insect
Photo: Coliner · CC BY-SA 4.0
Banana weevil (Cosmopolites sordidus) is a hard-shelled, dull-black, night-active beetle of banana and plantain. Adults barely fly and hide by day in damp litter and crevices around the base of the mat, so they spread mostly by walking — and by hitching a ride inside infested suckers. The real harm is done underground by the creamy-white grubs, which bore a dense network of tunnels through the corm (the underground stem) and the base of the false trunk. Damage builds up quietly over the plant's perennial life and is worst in old, poorly managed mats, where weakened plants throw small bunches and topple at the base.
Plant pests and diseases · CC0 
Plant pests and diseases · CC0
Why it matters
Banana weevil is a slow, hidden thief. Its grubs tunnel through the corm — the underground stem that anchors the plant and feeds the bunch — so plants grow weak, carry small bunches, and finally snap off and topple at the base, often just as the bunch fills out. A bad, long-standing attack can cost you up to 60% of your harvest. It is so hard to beat once it takes hold because the grubs live sealed inside the corm where no spray or hand can reach them, the pest quietly builds up in an old mat year after year, and it rides into your clean fields hidden inside infested suckers. That is why the whole battle is won before you plant — with clean material — and by trapping the adults early, long before the mat is riddled.
When to act
Average of more than about 5 weevils per split-pseudostem or disc-on-stump trap per week, or fresh tunnelling seen in the corm at planting or harvest.
This guidance is general, compiled from published agronomic references including FAO and CABI. Thresholds and timing shift with your crop, your variety and the season.
In much of the region a spray is simply called mushonga — medicine. But a chemical group you cannot name is one you cannot rotate, and a product you did not write down has no pre-harvest interval you can observe. Mushonga, and other farming words →
The full banana weevil field guide
- Identify it
- Scout for it
- Control it
14 field-guide sections in the app
The full guide to banana weevil — every symptom to check, how and when to walk your field looking for it, and the controls that actually work, ranked. Built into your crop plan, so you are told to look before it costs you a harvest.
Crops it affects
Frequently asked questions
How do I identify banana weevil?
The damage you see first: plants that grow weak and stunted, throw small, poorly-filled bunches, and then snap off or topple over at the base — often just as the bunch gets heavy or a strong wind comes through. Slice open the underground stem (the corm) and you will find it riddled with dark tunnels about the width of a pencil, sometimes with a soft, rotten smell where the tunnels have let rot creep in.
When should I take action against banana weevil?
Average of more than about 5 weevils per split-pseudostem or disc-on-stump trap per week, or fresh tunnelling seen in the corm at planting or harvest.
How do I control banana weevil?
Prevent it — start clean. The weevil rides into new fields hidden inside infested suckers, so never plant a sucker straight from an old, infested mat. Use tissue-culture plantlets, or pare your suckers — trim off all the roots and the outer skin of the corm with a knife until the flesh is clean and white, cutting out any tunnels or grubs you uncover. For extra safety, dip the pared suckers in hot water (about 50–55°C — hot but not boiling) for 15–20 minutes to kill any hidden eggs and grubs before you plant. This is your strongest single defence.
Which crops does banana weevil affect?
Among the crops covered here: Banana & plantain.
Catch it before it costs you a harvest
Divisi builds scouting into your crop plan — it tells you when to walk your field, what to look for at that stage, and what to do when you find it. Free for farmers, works offline.
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