Divisi
Red spider mite
Tetranychus urticae · Mite
Photo: Gilles San Martin · CC BY-SA 2.0
Red spider mite (Tetranychus urticae) is a sap-sucking mite — barely the size of a speck of ground pepper — that lives in colonies on the underside of leaves. It stabs the leaf cells and drinks them dry, so the leaf loses its green, turns dull and bronzed, then yellows and drops early. It breeds fastest in hot, dry, dusty weather (about 25–35°C), when a colony can multiply in a few days and spin fine silk webbing over the leaves and growing tips. It hits a wide range of crops — tomato, beans, cassava, cotton and eggplant among them.
Natalka Ukraine (baby-bear.org) · CC BY 4.0 
Excellens25 · CC BY 4.0
Why it matters
Red spider mites are tiny, but they can strip the life out of a crop: a bad, unchecked attack can cost you up to 60% of your harvest — more than half of what you were counting on. They breed fastest in hot, dry weather, so a few mites on a couple of leaves can explode into a webbed, dying patch in a week or two. Once the colony is big and spinning silk over the leaves, sprays struggle to wet the mites hiding underneath, and the mites quickly stop responding to the same chemical — so the only cheap win is catching them early, while they are still a small, spreading patch.
When to act
Fine stippling and mites visible on the underside of leaves on a spreading patch of plants, before webbing becomes general
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 red spider mite field guide
- Identify it
- Scout for it
- Control it
12 field-guide sections in the app
The full guide to red spider mite — 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 red spider mite?
The first thing you notice is the leaves losing their colour. A fine sprinkle of pale, silvery-white or yellow dots — called stippling, as if the leaf was dusted with tiny pin-pricks — shows up on the upper side of the leaves. As it worsens the whole leaf goes dull and bronzed or rusty, then yellows, dries at the tips and edges, and falls early. It almost always starts on the older, lower leaves and along the hot, dusty edge of the field.
When should I take action against red spider mite?
Fine stippling and mites visible on the underside of leaves on a spreading patch of plants, before webbing becomes general
How do I control red spider mite?
Prevent it — keep plants strong and cool. Mites explode on thirsty, dusty, over-fed plants. Water enough that the crop never wilts, and in the heat wash the dust off the leaves with plain water — a dusty leaf is a mite nursery. Go easy on nitrogen fertiliser, because soft, over-lush growth feeds mites. And pull out the weeds in and around the field, since they carry mites over from one crop to the next.
Which crops does red spider mite affect?
Among the crops covered here: Cassava, Common bean, Cotton, Eggplant, Tomato.
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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