As the rainy season approaches, there is a surge of activity in the dried-up ponds. These are ideal breeding places for the mosquitoes. At the bottom of ponds and in every hollow that is likely to fill up with water, mosquitoes can be seen on the move, but they are walking around rather than flying, as though intent on finding something.

Mosquitoes, normally thought of as fliers, present an interesting sight as they try to walk over obstacles that are like mountain peaks compared to their own size. All at once, thousands of mosquitoes go into action, as though they have received an order from somewhere. Now it is time for them to do their duty.

The long journey of the detector mosquitoes...

Mother mosquitoes have to find a suitable place for their eggs. The young emerging from their eggs need water in order to complete their stages of growth. This can be a muddy pool left by the rain, a swamp, a paddy field, a swimming pool or even a few drops of water in a tin can. Mosquitoes have a preference for still water, as this kind of water contains plants that can photosynthesise and thus enrich the water with oxygen, which is one of the most important requirements of the larvae.

The mosquito eggs can develop in any environment where there is water, but even so, a certain set of conditions is required. The hatching larvae have to go through various stages of development before they become mature mosquitoes, and at each stage the young mosquitoes have different needs. Moreover, drought or severe heat can hinder the development of the eggs. For this reason, the mother mosquito has to find an environment in which the young she will produce can comfortably complete their development.

So how does the mosquito find the most suitable environment? By sight, by smell, by guesswork, or by coincidence?

Let's illustrate with an example the difficulty the mosquito faces in finding the most suitable place for its eggs. Imagine you are trying to reach somewhere in a place that is full of hills, trees and hollows and you are walking under the hot sun without any means of help like a sunshade or a vehicle. You can imagine how tiring such a journey would be.

When we think how small a mosquito is, we can imagine how difficult, even impossible it could be to find a suitable place. However, the mosquito does this effortlessly and lays its eggs with ease. Thanks to a special receptor on the underside of its abdomen, it can determine whether the moisture content and temperature of the ground make it a suitable place for the eggs. It scans the ground tirelessly to find the most suitable place.