Insects and the Smell Factor

Published: 03rd September 2015 10:24 AM  |   Last Updated: 03rd September 2015 10:24 AM   |  A+A-


This incident took place in California. The sky became cloaked with dense, black, ghastly clouds of smoke. For three days, hundreds of firemen tried in vain to douse the fire from which the smoke was coming. Fire-dousing engines from neighbouring states rushed in to help, along with local braveheart volunteers.

Unnoticed by anyone, a man was loitering close to the oil-tank that had exploded and given birth to the deadly fire. This man seemed composed in his thoughts and actions. When everybody was busy trying to tame the fire, he was engaged in catching flies! Finally, the policemen took notice of this man and his antics. They found him to be a scientist, a zoologist. 

No wonder many people regard scientists as mentally challenged beings engrossed in their own world, far from practicality. They do strange things to understand the cosmos.

Perhaps this man with his weird ways was trying to figure out some truth of nature by getting perilously close to the fire.

 People hesitated to stop him or they were too awed by him to do so.

wildlife.JPGThey obviously did not understand that the scientist was trying to find flies near the explosion site. Incidentally, this man happened to come to that part of California on that day. He noticed that hundreds of flies filled the sky like insignificant spots. The scientist managed to catch a fly and confirmed that it was indeed a smoke-fly. They have been named so because of their tendency to fly towards the smoke and dust coming out of a volcano. The smell of the dust, and smoke of a fire attracts them.

However, on this particular day they were misled to believe that there was a volcanic eruption happening in California, when it was in fact an oil tank spitting fumes into the air.

The bigger question was from where did they flew in. The nearest forest was at least 80 kilometres from the site of the oil tank disaster! Did the flies actually come all the way just because they had sensed a fiery smoke here in California? Must be. But the journey turned out to be futile this time. After all, the smoke did not arise from a volcano.

Smoke often confuses and misleads insects. Sports enthusiasts, with an adrenaline rush in their body during soccer matches, often smoke profusely. This smoke rises up in the air and comes together to take the form of a smoke ball. Scientists in America have noticed that smoke flies rush towards this smoky concentration. They surely possess an immensely strong sense of smell.

However, these powers deny them one thing. They cannot understand the source of the smell. The smell is like a signal to them. The signal which shouts out and says, “descend”!

Indeed, when volcanoes erupt these flies rush towards the smoke. In the process, many lose their precious lives.

But there is a natural reason why they do this. Smoke flies lay their eggs on recently half-burnt trees and bushes. After some time, life returns to normal when young green leaves sprout from the bark of the once-burnt trees and tender grass cover the earth’s surface. It is then that the egg shells of smoke flies break and release new life, the larvae of smoke flies. Other insects generally avoid burnt areas and take a long time to return to areas that were swallowed by fire. As a result, the larvae enjoy a buffet of food, untouched by anyone, hence not necessarily shared. Plus no predators would be lurking around.

Its not only fireflies, other insects too are efficient when it comes to providing food resources to their newborns. Just look at the commonest of them – Cabbage butterflies. Even though you see them hovering over many trees, they will only lay their eggs on cabbages. In the absence of cabbages, they will lay their eggs on similar vegetables.

Thus, you can be sure that parent butterflies instinctively know that cabbage like vegetables are food for their children. Cabbages indeed contain elements without which the larvae would die.

How do the parents understand? The answer lies in smell again. The cabbage gives out a smell to the butterflies that tells them “Come here my dear. I will provide your children with sumptuous dinners!”

Such is the hypnotism of smell for insects!

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