These are one of the most troublesome pests of plants grown under glass. The small, white, moth-like adults and the greenish-white scale-like larvae that occur on lower leaf surfaces both feed by sucking sap, and they excrete a sugary substance known as honey-dew. This makes the foliage sticky and allows the growth of a black, sooty mould. The larvae are fairly tolerant of most insecticides, unlike the adults which can be controlled by insecticides containing pyrethrum, biores-methrin or resmethrin.
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