Thrips (also called Thunder Flies) are yellow-black, very thin and about 2mm long. Yet another sap feeding insect but one with a difference: this one will happily feed on the surface of a leaf.
Look out for mottled and discoloured leaves, with signs of bleaching. Thrips can also spread virus diseases through their mouths increasing the risk of fungal infection.
Treatment and control
Spray with a natural-based organic insecticide: Products containing fatty acids and sulphur will clear infestations. An example is BugClear Ultra Gun! which will not only rid you of Thrips but will help protect against disease. Decorative, ornamental plants can be sprayed with a systemic insecticide to give excellent control. Examples are BugClear Ultra and BugClear Ultra Gun! which both contain acetamiprod.