Divisi
Sunflower head moth
Homoeosoma nebulella · Insect
Photo: Ilia Ustyantsev from Russia · CC BY-SA 2.0
The sunflower head moth (Homoeosoma nebulella) is a small grey moth whose caterpillars — not the moth itself — do the harm. The moths settle on sunflower heads as the petals open and tuck their eggs among the tiny disc flowers; the caterpillars that hatch first graze on pollen and florets, then bore into the soft, filling seeds and spin a dirty mat of silk webbing and droppings across the face of the head. Hollowed seeds plus a damp, webbed head also open the door to head rot. Sunflower is its only crop host.
Ben Sale from Stevenage, UK · CC BY 2.0 
Ben Sale from Stevenage, UK · CC BY 2.0
Why it matters
The caterpillars eat your seeds from the inside, and a bad attack can wipe out up to 40% of your harvest — almost half the crop you were counting on. Worse, the silk they weave across the head traps moisture and invites head-rot fungus, so a webbed head can rot as well as empty out. And once the caterpillars have tunnelled down into the seeds, no spray can reach them — so the whole fight is won or lost in the few days the flowers stand open, when you must strike at the moths and eggs before they get inside.
When to act
Treat at early flowering when 1-2 moths per plant are seen at dusk or the first eggs and young larvae appear on the face of opening heads.
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 sunflower head moth field guide
- Identify it
- Scout for it
- Control it
15 field-guide sections in the app
The full guide to sunflower head moth — 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 sunflower head moth?
The damage shows first — look for webbing. The clearest sign is a dirty mat of silk webbing spun across the open face of the flower head, tangled with sticky brown droppings called frass — as if a spider had fouled the flower. Peel the webbing back and the seeds beneath are hollow, chewed and tunnelled; a badly webbed head often turns dark and starts to rot.
When should I take action against sunflower head moth?
Treat at early flowering when 1-2 moths per plant are seen at dusk or the first eggs and young larvae appear on the face of opening heads.
How do I control sunflower head moth?
Prevent it — plant an armoured variety. Your single strongest defence is a modern hull-armoured sunflower: its seed hulls carry a hard black armour layer (called phytomelanin, a kind of natural bullet-proof coat) that stops the young caterpillars boring in. Ask your seed dealer or extension officer for an oil or confectionery variety bred to resist the head moth.
Which crops does sunflower head moth affect?
Among the crops covered here: Sunflower.
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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