Divisi
White grubs
· Insect
Photo: Rasbak · CC BY-SA 3.0
White grubs are the fat, soil-dwelling larvae (the young, worm-like stage) of scarab and chafer beetles. Curled like a white "C" with a hard brown head and three pairs of legs near the front, they live hidden in the soil and feed on roots, tubers and the underground stem — cutting your plants off from the water and food in the ground. The adult beetles fly out with the first rains, often to lights at night, and lay their eggs in moist, loose soil, so the grubs are worst in damp, organic-rich fields and where the same host crop (maize, groundnut, sorghum, potato or sugarcane) is grown year after year.
Cindy kuiphuis · CC BY-SA 4.0 
Сарапулов · CC BY 4.0
Why it matters
White grubs do their worst damage out of sight, underground, chewing through the roots and tubers that feed your plants. By the time you see seedlings wilting and dying in patches, the roots are already gone and those plants will not recover — a bad attack can cost you up to 40% of your crop, close to half. They are hard to beat once they are in the soil, because sprays on the leaves never reach them: the real fight has to happen at planting and in the soil, before the grubs grow big.
When to act
Patches of wilting or dead seedlings with grubs found on digging, or a history of grub damage in the plot.
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 white grubs field guide
- Identify it
- Scout for it
- Control it
13 field-guide sections in the app
The full guide to white grubs — 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 white grubs?
The first sign, above ground: healthy-looking plants suddenly wilt, yellow and die in scattered patches — not the whole field at once — and the patches often spread outward over a few days. Dead and dying plants pull out of the ground easily, because their roots have been chewed away.
When should I take action against white grubs?
Patches of wilting or dead seedlings with grubs found on digging, or a history of grub damage in the plot.
How do I control white grubs?
Prevent first — turn the soil and let the birds feed: plough or dig deeply before planting to throw the grubs up to the hot sun and to the chickens, birds and ants that eat them, and hand-pick and crush every grub you turn up during land prep. This is your cheapest and safest weapon.
Which crops does white grubs affect?
Among the crops covered here: Groundnut, Maize, Sorghum, Sugarcane.
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.
Check what grows on your farm