Thrips
Thrips are minute slender insects, some of which feed on the undersides of leaves. Because of their small size, these animals are not obvious, and it is their damage one notices: plant leaves look bleached or silvery, and the undersides are often spotted black with frass (droppings). Usually the older leaves are affected, and the visible damage is accompanied by a foul odor. We do a paper-shake test to see if thrips are present, and we commonly find them on plants we shear, such as myrtle and viburnum. Open pruning helps to improve air circulation and provide access for beneficial insects.