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Pests: find out more SCALES
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The Pest
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There are two broad categories of scale insects. The Diaspidae and the Lecanidae.
The Diaspidae are also known as hard or ‘armoured’ scales and comprise many species but each has a limited host range. There is no biological control currently available for control of these scales. The Lecanidae, or soft scale, have two common species. Coccus hesperidum (brown soft scale) is oval in shape, light brown, green or grey in colour with black-brown patches and to 4mm long. Saissetia coffeae (hemispherical scale) is larger, more dome shaped, shiny and deep brown in colour. Larvae of both species are flat and difficult to differentiate from other scale species. Soft scale is a common pest on foliage plants, in interior landscapes and tropical houses. In common with aphids and whitefly, soft scales feed on plant sap causing distortion, yellowing and defoliation. Honeydew is also secreted which can encourage the growth of sooty moulds.
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Scale nymphs
Scales saissetia
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Life Cycle
The life cycle for S. coffeae takes 95 days at 18°C and 51 days at 28°C. Females produce masses of eggs before they die and the eggs are protected under her scale cover. After emerging from the egg the young scales (crawlers) must find suitable feeding sites. They move to other parts of the plant, such as plant stems and near leaf veins where they settle to feed from the phloem. Once settled they then become an immobile scale. Although the life cycle of soft scale is relatively slow, the high numbers of offspring lead to large infestations if left uncontrolled. With C. hesperidum the female produces up to 250 live young. | |
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