Divisi
Yam beetle
Heteroligus meles · Insect
Photo: Noël Mal · CC BY-SA 4.0
The yam beetle (Heteroligus meles) is a big, hard-shelled brown-black beetle — a relative of the rhinoceros beetles — that lives and feeds in the soil. It is the adult beetle, not a grub, that does the harm: the beetles breed in swampy, waterlogged ground and fly out to yam fields with the rains, then burrow down and bore clean, round holes straight into your growing tubers. Because it hides in the soil by day and feeds at night, you rarely see the beetle itself — you see the holes when you dig.
Airypedia · CC BY-SA 4.0 
Sasu photography · CC BY-SA 4.0
Why it matters
The yam beetle attacks the one part of the plant you actually eat and sell — the tuber — so its damage goes straight to your income. A bad attack can spoil up to half your yams (50%), and even a few holes drop a tuber to a low market grade, make it rot quickly in storage, and ruin it as seed-yam for next year. It is hard to beat once it settles in, because the beetle works underground and inside the tuber, out of sight and out of reach of any leaf spray — you often don't know it is there until you dig up a holed tuber, and by then the damage is already done. Fields near swampy ground get re-invaded every season, so the problem keeps coming back year after year.
When to act
Fresh feeding holes on tubers found in cut-tests, or a history of yam beetle damage in the area; act during the main migration and feeding period.
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 yam beetle field guide
- Identify it
- Scout for it
- Control it
16 field-guide sections in the app
The full guide to yam beetle — 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 yam beetle?
The damage you see first: clean, round holes about the width of a finger bored straight into the tuber, often with tunnels running deep into the flesh. Fresh holes are pale and moist inside; older ones turn brown and start to rot. A holed tuber can look fine from the top while it is eaten out below — you usually only find the damage when you dig or lift the tuber.
When should I take action against yam beetle?
Fresh feeding holes on tubers found in cut-tests, or a history of yam beetle damage in the area; act during the main migration and feeding period.
How do I control yam beetle?
Prevent — plant early: get your yams in early, before the main beetle migration and feeding period, so the crop is well established and you can lift it before beetle numbers peak. Early planting is one of your strongest defences against this pest.
Which crops does yam beetle affect?
Among the crops covered here: Yam.
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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