Divisi
Diamondback moth
Plutella xylostella · Insect
Photo: Dan MacNeal · CC BY 4.0
The diamondback moth (Plutella xylostella) is the number-one pest of the cabbage family — cabbage, kale, rape, broccoli and cauliflower. Its small, pale-green caterpillars scrape the underside of the leaves and bore into the growing point and the forming head, spoiling the very part you sell. It breeds fast, stacking generation on generation through a warm, dry season, and is famous the world over for shrugging off sprays that once killed it — so beating it means catching it early, protecting the natural helpers in your field, and never trusting one chemical alone.
Markus Krieger · CC BY 4.0 
Merle Shepard, Gerald R. Carner & P.A.C. Ooi, Insects and their Natural Enemies Associated with Vegetables and Soybean in Southeast Asia, Bugwood.org · CC BY 3.0 us
Why it matters
Left unchecked, the diamondback moth can strip up to half (50%) of your cabbage or kale crop. Because the caterpillars chew straight into the growing point and the forming head, they ruin the exact part you take to market — not just a few outer leaves you could trim off. It breeds fast in warm, dry weather, throwing one generation after another at your field, so a handful of caterpillars becomes a swarm within a couple of weeks. Worst of all, it is the most spray-resistant pest of the cabbage family in the world: keep hitting it with the same chemical and it simply stops dying — which is why you must catch it early and lean on prevention and natural helpers, not just a spray bottle.
When to act
Treat when 1 or more larvae per plant on seedlings, or 10 to 20 percent of plants infested at heading.
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 diamondback moth field guide
- Identify it
- Scout for it
- Control it
21 field-guide sections in the app
The full guide to diamondback 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 diamondback moth?
The first sign — 'windows' on the leaves: turn a leaf over and look at the underside. You'll see pale, papery patches where the caterpillar has scraped away the green flesh but left the thin top skin, like tiny see-through windows. As these dry they tear into small ragged shot-holes, so the leaf looks peppered with little holes.
When should I take action against diamondback moth?
Treat when 1 or more larvae per plant on seedlings, or 10 to 20 percent of plants infested at heading.
How do I control diamondback moth?
Prevent — break the breeding cycle: don't grow cabbage-family crops on the same land season after season. Rotate to a non-brassica such as maize or beans, and the moment you finish harvesting, pull out and burn or bury the old stalks and leftover leaves — the moth keeps breeding on them and walks straight into your next crop.
Which crops does diamondback moth affect?
Among the crops covered here: Cabbage, Rape / covo / kale.
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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