Divisi
Beet leaf miner
Pegomya hyoscyami · Insect
Beet leaf miner is the maggot of a small grey fly (Pegomya hyoscyami) that attacks the beet family — beetroot, Swiss chard and spinach. The fly lays little white eggs on the undersides of the leaves; the maggots hatch and tunnel inside the leaf, eating the green between the upper and lower skins and leaving pale, blister-like blotches. Several overlapping generations appear through a mild season, and the maggots can crawl from one leaf to the next as they feed.
Why it matters
Beet leaf miner is the maggot of a small fly, and it eats your spinach, chard and beetroot leaves from the inside. A bad attack turns pale, papery blisters across up to 40% of your leaves — and on leafy crops you sell by the leaf, a mined leaf is worthless, while on beetroot the ruined leaves starve the root and shrink your harvest. Because the maggot feeds hidden between the two skins of the leaf, a spray can't reach it once it is inside, and the fly breeds generation after generation off nearby weeds — so the only real cure is to stop it laying eggs and to catch it early, before it burrows in.
When to act
Fresh mines or clusters of white eggs on leaf undersides on 1 in 5 plants, especially on young leafy crops grown for the leaf.
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 beet leaf miner field guide
- Identify it
- Scout for it
- Control it
17 field-guide sections in the app
The full guide to beet leaf miner — 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 beet leaf miner?
The damage you see first: pale, winding lines or blister-like blotches on the leaves of spinach, chard and beetroot. They begin as thin, pale squiggles and swell into papery patches that turn from see-through green to brown and dry. Hold a leaf up to the sunlight: a mine (the fed-out patch) is hollow — you can see right through the skin, and often spot the small maggot or its dark specks of droppings inside.
When should I take action against beet leaf miner?
Fresh mines or clusters of white eggs on leaf undersides on 1 in 5 plants, especially on young leafy crops grown for the leaf.
How do I control beet leaf miner?
Prevent it — starve the fly: clear away goosefoot weeds such as fat hen (lambsquarters) and orache in and around the plot. These weeds feed the fly between crops and let it survive to attack your beds.
Which crops does beet leaf miner affect?
Among the crops covered here: Beetroot, Swiss chard.
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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