Thrips

Symptoms
Leaves of infested plants become dull-green and develop a silvery-white colour on the surface. Tiny black spots may appear on leaves and eggs can be seen on young leaves and in flower buds. Shoot tips and flower buds both become distorted if they have been damaged by the insects' feeding. Flower petals may be flecked white where pigment has been lost, and flower buds may fail to open. May lead to other problems such as a pelargonium virus.

Spot them
There are a number of different thrips species. Adult thrips vary in colour from yellow-brown to black and some have a banded appearance.