Monday, January 12, 2009

Mayfly - Shortest Life Span
Mayflies can be easily recognised by the tails t heir rear. They spend their egg and nymph stages underwater, where fish often eat them. That is why fly-fishermen often base the artificial flies they make of mayflies. These insects also frequently fly into houses, especially at night, when they are attracted by lights. From their name, that these insects are only to be found during one month. However, they are out and about in many parts of the world throughout the summer – but only for a day or so. The order to which mayflies belong us know as “Ephemeroptera”, meaning “winged creature living for a day”. The nymph stage, however, may last up to two years.
Sometimes a mayfly may emerge in the evening and not even last until the following morning. A few, however, live for as long as a week but can not feed because their mouthparts are closed and their stomachs full of air. Longer-living mayflies may sometimes keep their eggs inside their bodies until they are ready to hatch. But normally by the time that mayfly eggs hatch which normally takes between two to five weeks – both parents are long dead and each emerging larva is an orphan. The mayfly nymph lives underwater and has biting mouthparts for feeding on small aquatic creatures or plants.
A male mayfly is about to take to the air for the first time and has just begun his adult life. After only a few hours of flying, like others of his species, he will start to feel tired, and food reserves will be running low. Soon he joins a swarm holding vast numbers of his kind, and all begin the search for mate. There is great competition for females who enter the swarm from above, sometimes flying as high as fifty feet. After dancing up and down for a while, his enlarged eyes which are far bigger in the males than in female mayflies, find a partner and they get together in the air. Before long, he is too exhausted to fly any further and slowly settles on the ground. By morning he is dead of old age, the female will have returned to the water. In the water her body will literally explode as she releases her minute eggs.
Toady mayflies are known to be highly sensitive to pollutants. They are therefore frequently used as bio-indictors by water authorities who study the water purity of water courses.
Yuwaraj Gurjar.

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