Wednesday 4 June 2014

Brown scale insect

A garden ant stimulated this scale insect to produce honeydew with her antenae. Some these scale insects, Parthenolecanium corni, are growing on a grapevine branch, just under strips of bark. They are about 5 mm, dark and shiny, with ridges across. When young, they are tiny and mobile and are called crawlers, and live under leaves. When they are ready to moult into the immobile scale stage they move into branches. Scale insects, as aphids, suck the sap of plants, and excrete a sugar rich liquid call honeydew, which ants like.

 These scale insects can become a pest of various fruit trees. The scale insect has natural enemies, though. Parasitoid wasps inject their eggs into the scale insect, and the larvae will emerge though holes in the scale, instead of the crawlers. A parasitised scale insect after the wasps emergence is shown below.

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