Flies perhaps not so pesky

robber fly feeding on a small insect

Flies perhaps not so pesky

April 2016 | Sarah Lloyd

FLIES BELONG to the order Diptera (di = two; ptera = wing), one of four mega-diverse orders of insects.

The other mega-diverse orders are the Coleoptera (beetles) Lepidoptera (moths and butterflies) and Hymenoptera (wasps, ants and sawflies).

Insects with ‘fly’ in their name including dragonfly, mayfly and butterfly have two pairs of wings whereas most flies have only one. Their second pair is reduced to small club-shaped structures called halteres that are situated behind the wings.

When flies fly the halteres vibrate and act like tiny gyroscopes. This allows flies to hover, fly backwards, rotate on their own axis and fly through spaces a little wider than their wings.

The thorax of flies is simpler than the thorax of other insects. The first and last segments are almost non-existent, while the middle section is greatly enlarged and entirely made up of wing muscles. This feature permits fast flying, a high degree of manoeuvrability and very fast wing beat frequencies (up to 1000 beats per minute in tiny midges). It also means that flies have great control over their direction and position of landing sites – not many insects can land upside down on ceilings!

Most adult flies have a liquid diet of water, nectar or blood. It is the blood feeders that give the group a bad name because they spread diseases such as malaria and zika virus – amongst others.

However, most flies go unnoticed as they play their important ecological roles of pollinating plants, cleaning up rotting vegetation, carcasses and dung, and predating other insects. Furthermore, flies are an important food source for birds, frogs and reptiles. Without flies the world would  be a very different place – may your flies be interesting and not pesky!