Saturday, November 3, 2012

A flying huntsman

It is again the time of the year when the high temperatures do not encourage you to take long walks in the countryside. 

Most vegetation is completely dry and even the perennial plants and that are well adapted to survive the dry Mediterranean summer reduce their rate of growth to a bare minimum.

Butterflies are noted by their absence although other insects such as the various species of bees and wasps remain very active throughout the day. Some species of dragonflies are also active during the summer months. 

Dragonflies live close to water. Adult dragonflies are often seen hunting smaller insects near pools and ponds. They also need water to breed. Dragonflies lay their eggs in water. Some insert them in floating or submerged vegetation; others drop them onto the water while flying. 

The larvae live a completely aquatic life. They are important predators feeding on other invertebrates especially mosquito larvae and so help to control their numbers. As they get older, the larvae start hunting larger prey, including vertebrates such as tadpoles. 

The larval stage is much longer than the adult stage. Some species remain under water for several months; others for up to five or six years. 

When the larval stage is completed the larva climbs out of the water, usually up a reed or other vegetation. In Malta seen larvae living in cement-lined reservoirs get a foothold on dry algae growing on the vertical sides of the reservoir.

On emerging from the water the larva starts breathing air. The larval skin breaks open along a weak spot behind the head and the adult dragonfly walks out of its larval skin to start life as a flying and hunting machine. 

Some dragonflies can fly large distances. A few species can migrate and even cross relatively large sea crossings, such as between Malta and Sicily. 

This article was published in The Times on 15.08.2012

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