Fine pale mottling
Numerous tiny feeding punctures merge into a dull, speckled or bronzed appearance. Damage often begins on older or sheltered leaves.
Webbing is a late clue. The earlier signal is fine pale mottling on leaves, especially in a warm, dry greenhouse. Despite the name, feeding mites are often yellowish-green with two darker patches in spring and summer.
Start with the quick check ↓Quick check
What to inspect now
Hold a suspect leaf against the light and inspect its underside with a hand lens. Look for fine pale speckling, tiny moving mites and delicate webbing around veins.
- Main timing
- Usually most troublesome March–October, especially during warm, dry weather; possible year-round in a heated greenhouse.
- Plants affected
- Tomatoes, cucumbers, peppers, aubergines, beans and many greenhouse or house plants.
Identification
Signs that narrow it down
Mites under the leaf
Summer mites are generally yellow-green with two dark patches and are less than 1 mm long. They are easier to see with magnification.
Fine webbing
Silk between leaves and stems indicates a larger population. Do not wait for heavy webbing before inspecting nearby plants.
If you confirm it
Useful action, in order
Start with the least disruptive step that protects the crop. The presence of a pest does not automatically justify treatment.
- 1
Isolate and inspect
Separate movable affected plants and inspect everything nearby, including weeds and ornamentals that can host mites.
- 2
Remove the worst leaves
Bag heavily infested foliage without stripping so much leaf area that the crop is weakened. Clean up fallen debris and supports.
- 3
Use biological controls early
Predatory mites work best within stated temperature and humidity ranges and before an infestation becomes overwhelming. Follow supplier instructions precisely.
Next crop
Reduce the chance of a repeat
Avoid hot, parched stress
Water crops consistently and ventilate the greenhouse. Raising humidity can make conditions less favourable, but avoid prolonged leaf wetness and poor airflow.
Inspect weekly in warm spells
Check the undersides of a few leaves from several plants; early mottling is much easier to manage than widespread webbing.
Clean between crops
Remove host weeds and crop debris and clean empty greenhouse structures where resting females may shelter.
Common questions
Practical answers
Why are red spider mites not red?
Feeding mites in spring and summer are often yellowish-green with two dark patches. Females commonly turn orange-red when resting in autumn and winter.
Does misting kill red spider mite?
Higher humidity makes conditions less favourable but does not reliably control an established population on its own. Combine good growing conditions with inspection and an appropriate control.
Can red spider mite affect outdoor vegetables?
Yes. It is best known under glass but can damage outdoor plants during hot, dry summers.
Sources and scope
Evidence behind this guide
SowNext summarises identification, timing and lower-impact management for UK home food growing. Local populations and protected conditions can differ, so confirm the organism before acting.