BIOLOGY OF BEETLES

These insects resemble the Cockroach in having biting mouth-parts but their elytra are thicker. Unlike the Cockroach their life history displays a complete metamorphosis.

THE LADYBIRD BEETLE

This well-known beetle is easily recognized by its small oval shape and its brightly coloured elytra which in the commoner species are scarlet with black spots.

The adult beetles hibernate in cracks in the bark of trees or in other sheltered spots and emerge in late spring. The females lay their eggs on plants such as roses which are liable to attack by aphides.

The larvae which hatch out from the eggs are called ’niggers. ’ They are slaty-blue or black in colour with a few orange, yellow or white spots along their sides and feed voraciously on the aphides. When fully grown they pupate on the undersides of leaves and in about a fortnight the adult beetles emerge from the pupal skins and recommence feeding on the aphides. Both beetles and larva? therefore perform most useful work in checking the numbers and spread of aphides which damage plants severely by sucking their sap.

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