There are two main groups of scale insects, both of which spend most of their lives as immobile adults under a coating, sucking the sap from stalks, leaves and stems.
Hard scale (for example red citrus scale) has an oyster like coating and is difficult to control. Also known as armoured scale.
Soft scale (for example pink wax scale and soft brown scale) are usually found on the mid-rib of leaves and stalks of host plants.
Most common is white wax scale, seen as large patches of white waxy material along the stems and shoots. The wax covers the insects which feed on the sap. The adult scale lays up to 1000 eggs that hatch into crawlers. These crawlers move to a nearby feeding site where they set up home feeding on the sap of the plant. It is at this crawler stage the scale is most vulnerable as there is no waxy coating to protect them.
Turn the leaves over and look for small raised bumps. Scale insects are tiny creatures that hide underneath a protective covering and suck the sap out of leaves.
Yates Nature’s Way Citrus & Ornamental Spray is a ready to use, organically certified blend of pyrethrin (an extract from the pyrethrum daisy) and vegetable oil. Regular spraying on the undersides of the leaves (so it comes into direct contact with the scale) will help bring scale insects under control.
NOTE: There are other different types of scale and some scale insects are host specific, such as rose scale, white palm scale, gum tree scale and tea scale (camellias). Others attack a variety of hosts such as white wax scale occurring on gardenias and citrus; and cottony cushion scale occurring on figs, rose, magnolias, grevilleas and citrus.
If your citrus tree is dropping leaves, twigs and branches are dying back, and/or the fruit is stunted or distorted. If you’ve noticed small yellow spots appearing on your citrus leaves any of these symptoms may indicate an infestation of citrus scale pests.
Other signs are white patches on stems or pink or brown raised dome like structures on leaves and stalks about 3-5mm.
Sooty mould grows on the honeydew the scale insects secrete. Scale can cause death of stems if infestation is heavy.