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Sooty beech scale insect

Sooty beech scale insect

Unlike the beech trees (producers), animals cannot make their own food from raw carbon dioxide, water and light energy. All animals must eat (consume) food for survival and are called consumers. Beech trees provide food for many native leaf-eating and wood-boring insects.

One of them is the scale insect (Ultracoelostoma assimile), the sap sucking bug which makes honeydew, a sugary substance that is eaten by other native insects, like beetles and moths, and birds such as tūī, bellbirds and kākā. Lizards, possums, rats, honeybees and wasps have also been seen feeding on honeydew.

Sooty scale insects live within the bark of beech trees. They have a very simple body structure, the shape of a tiny floppy hat, with no wings or legs. They are just mouthparts with a very long anal tube. The latter is the part of the insect that you can see protruding as a thin waxy stem from the bark of the tree. The tube often has a small drop of sweet sugary, and edible, honeydew at the end.

The sugary sap from the beech tree provides the scale insect with more than it needs to live, therefore the scale insect secretes (gets rid of) the excess sugar through its anal tube, forming small droplets that are eaten by birds or fall to the forest floor.

(Information from: Science Learning Hub website.)

While native animals harvest the honeydew without harming the scale insect, introduced wasps are very greedy, and kill the scale insects by damaging their anal tube.

Sooty scale insects are particularly common in beech forests at the foothills of the Southern Alps, but seldom noticed in the Kepler area. The photos below were taken along the stoatline checked by Fiordland College students and staff.

Did you know that honeydew is an excellent source of energy food for survival in the bush? The introduced honey bees harvest the sugary liquid to make honey, which beekeepers sell as one of the finest honeys in the world.

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