Morales, C.F., & Bain, J. 1989 Icerya purchasi Maskell, cottony cushion scale.. A Review of biological control of invertebrate pests and weeds in New Zealand 1874 to 1987. CAB International Institute of Biological Control Wallingford Oxon, U.K. 424 pp.

Notes: [Technical communication/CAB International Institute of Biological Control, No. 10]. Icerya purchasi Maskell, a native of Australia, became a very serious pest of citrus in California and South Africa in the 1870s. It was first found in New Zealand on kangaroo acacia in Auckland in 1877. It is now present in most subtropical, tropical, and many of the temperate areas of the world. It can be a serious pest on a wide range of wild and cultivated plants, espeially species in the genera Acacia, Citrus, Casuarina and Pittosporum. It is notable for its wide climatic tolerance and its severe effect on its host plants. It is usually found on twigs and branches but rarely on fruit or flowers, and in heavy infestations the plants appear to be covered with snow. Injury to plants is similar to that of other sap sucking insects, causing defoliation, fruit drop, and debility of the plant. The excretion of honey dew by the scales causes the growth of sooty mould fungus.