Hard to identify as they are microscopic, however, in summer, the damage they cause is easily identified.
The stems of the plant become bronzed, the lower leaves wither and die and the skin of the fruit becomes leathery.
Use neem oil or insecticidal oil
Use garlic spray to deter pests.
Crush 5-6 cloves of garlic and pour over 1 litre of boiling water.
Leave to cool and strain into a spray bottle.
If you add a teaspoon of liquid soap, this can help the spray stick onto the leaves.
Spray this liberally onto your plants and repeat in a couple of days time.
There is no danger of overdosing garlic spray so reapply whenever you like!
Mist the greenhouse with a fine water spray during hot weather.
Mites prefer dry conditions.
Higher humidity may encourage diseases though, so watch for signs of mildew.
Remove unwanted plants from greenhouse in autumn.