Divisi
Cotton stainers
Dysdercus spp. · Insect
Photo: Baruk Mazzaro · CC BY-SA 4.0
Cotton stainers (Dysdercus species) are conspicuous red-and-black sucking bugs that attack cotton from boll formation right through to boll opening. Adults and their wingless red young cluster on the bolls and pierce the wall with a needle-like beak to feed on the developing seeds. Their punctures carry staining moulds into the boll that discolour the lint, while the seeds shrivel with poor oil and low germination. Because they also breed on fallen bolls, loose seed and wild plants of the cotton and hibiscus family, they keep returning to the crop.
RidhaAnshari85 · CC BY 4.0 
Charles J. Sharp · CC BY-SA 4.0
Why it matters
Cotton stainers don't just eat your crop — they dirty it. As they suck on the bolls they carry staining moulds into the cotton, and once the white lint turns yellow, brown or black it can never be cleaned again — the buyer downgrades it and pays you less, so a bad attack can strip up to 40% of your cotton's value in low-grade lint and shrivelled, low-oil seed. They are hard to shake off because they breed on fallen bolls, loose seed and wild plants at the field edge, so they keep coming back — and they hit hardest late in the season, close to harvest, when spraying is riskiest. Catching them early and keeping the field clean is everything.
When to act
Clusters of the red-and-black bugs on developing or open bolls, or first stained lint appearing.
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 cotton stainers field guide
- Identify it
- Scout for it
- Control it
14 field-guide sections in the app
The full guide to cotton stainers — 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 cotton stainers?
The damage first: when you open a boll (the pod that holds the cotton) the white lint — the cotton fibre you pick and sell — is blotched yellow, brown or even black, as if it has been dirtied or rusted. This staining is the tell-tale sign, and it is exactly what makes a buyer downgrade your cotton and pay you less. On the outside of green bolls you may also see small greasy yellow-brown spots where the bugs have been sucking.
When should I take action against cotton stainers?
Clusters of the red-and-black bugs on developing or open bolls, or first stained lint appearing.
How do I control cotton stainers?
Prevent it first — keep the field clean and harvest on time (your strongest tool). Pick your cotton promptly and never leave open bolls hanging in the field, where the bugs feed and breed. Gather and destroy the fallen bolls and loose seed off the ground. After the last picking, uproot and burn or bury the old cotton stalks and trash so nothing carries the bugs over to next season.
Which crops does cotton stainers affect?
Among the crops covered here: Cotton, Roselle.
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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