Divisi
Sorghum midge
Stenodiplosis sorghicola · Insect
Photo: Harry Rose, Dungog, Australia · CC BY 2.0
Sorghum midge is a tiny orange fly — barely the size of a grain of rice — that attacks sorghum only while the head is flowering. The female slips her eggs into the open flower, and the small orange maggot that hatches eats the developing grain from the inside, so the spikelet (the little flower that should become one grain) stays empty and 'blind'. Because it strikes only at flowering, its damage is tied tightly to that short window and is worst when a field flowers unevenly or late.
Obatom19 (Wikimedia Commons) · CC BY 4.0
Why it matters
Sorghum midge can quietly take more than half your grain — up to 60% — yet you often don't notice until the harvest is already gone. The fly strikes only while the head is flowering, and its maggot eats each grain from the inside before it can even form, leaving a thin, half-empty head of blasted (empty) spikelets. Once the maggot is sealed inside the flower there is nothing you can spray to save that grain — and if plants in your area flower at different times, the fly keeps breeding from one late head to the next, so its numbers build fast. Your only real defence is a resistant variety and getting the whole crop to flower together, quickly.
When to act
About one adult midge per panicle at flowering, or where staggered flowering exposes panicles over a long 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 sorghum midge field guide
- Identify it
- Scout for it
- Control it
15 field-guide sections in the app
The full guide to sorghum midge — 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 sorghum midge?
The damage (look here first): at grain-fill you expect a full, heavy head. Instead the head looks thin and sparse — many spikelets (the little flowers that each should carry one grain) are flat, empty and 'blind', set no grain, while only a few here and there fill. Pinch an empty floret: there is nothing inside, or a tiny orange maggot. The surest sign it was midge: hold the head to the light and you'll see clear, whitish empty pupal cases (the little cases the young fly leaves behind) poking out of the spikelet tips like fine threads.
When should I take action against sorghum midge?
About one adult midge per panicle at flowering, or where staggered flowering exposes panicles over a long period.
How do I control sorghum midge?
Prevent — grow a resistant variety (your strongest tool): plant a midge-resistant sorghum variety if you can get one — this is the single most effective step. Resistant heads flower quickly and tightly and are far less suitable for the fly to breed in. Ask your extension officer or seed dealer which resistant varieties are sold near you.
Which crops does sorghum midge affect?
Among the crops covered here: Sorghum.
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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