Saturday, December 28, 2013

Why cicadas only sing in summer

The continuous buzzing sound of the cicada is typical of Maltese summer days.

The cicada appears punctually during the second week of July. The larva digs its way out of the soil in it had lived for many years. It then climbs up the nearest vertical object which is usually the trunk of the tree of which it had been sucking juices. Occasionally instead of a tree it finds a wall or other stone structure.

Once it is high enough it expands slightly and this causes its external skeleton to break along a weak line at its back. It then pushes itself out of the exoskeleton and slowly walks away from it. This is a very vulnerable moment for the now adult insect. Its new external skeleton is still soft and in case of danger it is not able to fly.

The new external skeleton and the wings do not take long to harden and soon the male cicadas start singing while the females start their search for singing males.

When a pair of cicadas meets, they start courtship and then they mate. Courtship consists of repeated hugging and touching each other with their legs.

Soon after, the cicada lays its eggs in the soil close to the surface. The eggs hatch in late summer or early autumn in well enough time for the newly hatched larvae to dig their way further down into the soil where they will be spending the rest of their lives as larvae.

Once mating takes place and eggs are laid adult cicadas have no further need to stay alive and start dying. The number of singing cicadas has started to decrease and soon the last one will stop singing leaving behind a silence that indicates that the end of the summer season is fast approaching. 

This article was published in the Times of Malta on 28 August 2013.

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