Pest Watch Scale insect control - Garden Scale Insects

Scale insect is a garden plant pest problem that can be difficult to control. Gardeners with scale insect problems may need to take measures to control them.
The adult scale insect is like a dark brown limpet, which attaches itself to the stem and branches of plants. It will attack a wide range of woody plants - including Japanese maples, bay trees, citrus (oranges and lemons), elaeagnus and numerous other trees , shrubs and even fruit trees and bushes. It can even attack the leaves; hydrangea scale being the most recognised scale insect pest that does this. Hydrangea scale insect attacks have been very bad in recent years.
The adult scale insects can be difficult to control, because the scale covering protects it from predators and is impervious to contact insecticides.
In spring and summer, the adults breed and the females produce a white, almost cotton wool-like substance, which are the eggs or egg mass, containing between 500 and 2,000 eggs, and then dies. The eggs hatch to produce a crawler stage, which settles on a suitable part of the plant, starts to feed and becomes immobile.
The length of the lifecycle depends on temperature, but it normally takes around 10 weeks from egg to adult.
Scale insects are sap suckers and a large infestation can weaken plants - especially small or stressed ones. They excrete honeydew, an almost pure sugar solution, on which black sooty mould will grow, causing the leaves of the plant to turn black.

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