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 The Cicada - 17 years underground!  
Throughout the tropics, the hot summer nights are punctuated by the sounds of insects. From the slow rasping of crickets to the rapid chatter of cicadas the night is alive with noise. During periods of rain or greater humidity they are joined by the chorus of frogs, also at this time seeking mates.  
Many insects find the open spaces of the world precarious places to live, and so they seek refuge in the water or under the soil, often remaining as larvae for long periods of time before becoming adults. The Mayflies of more temperate climates may only exist as adults for one day before dying. In that day they must find a mate and lay their eggs in a pond, river, or stream to perpetuate the species. Their life is of such an ephemeral nature of that the order to which they belong has been called the Ephemoptera.   

The Bahamian Cicadas, or ‘Singers’ as they are more popularly known, also have an extended larval period. A Cicada spends only two to three per cent of its life as an adult; the remainder being spent as a squat brown larva beneath the soil.
The females lay their eggs in paired slits, which they make on the twigs of trees. The eggs hatch in about six weeks and the young cicadas, now known as Nymphs, drop to the ground. The nymphs are somewhat similar to the adults except that they are fatter, have no wings or reproductive organs, and the front legs are strongly built for digging. They burrow down among the roots of trees on which they will feed for the next thirteen years. Some species of Cicada remain in the soil for as long as 17 years. During their period of growth in the ground they shed their skins several times, each nymph being a little larger than the one before.

After their subterranean larval stage, at a time that can be predicted with great accuracy, they emerge from the soil and climb two to four feet up the trunks of frees. Firmly attached by their forelegs, they now undergo the transformation into adults. The skin of the back splits and the soft-bodied adult pushes itself out through the split.

Now the Cicada has emerged it must rest while its wings expand and its body hardens. One and a half to two inches in length, it has four powerful membranous wings and a wide blunt head. Three beadlike simple eyes form a triangle between the larger compound eyes at the front corner of the head. The compound eyes, like those of other insects, are made up of hundreds of smaller units, each one of which can perceive light or darkness. The resulting image formed by such an eye must be similar to that seen on an old television screen, made up of only black and white dots.

The adult cicada will live for four to six weeks, feeding on tender plant stems or leaves. Only the males are capable of making the characteristic noise of the Cicada. They posses a pair of tymbal organs at the base of the abdomen, in which a special area of cuticle is made to vibrate at  about 4,500 cycle per second. Both sexes have well-developed hearing organs also at the base of the abdomen.

For the last few weeks of March the Cicadas have been hatching. The adults are now singing to each other as they seek their mates, their empty, fragile larval skins still hanging from the trunks of the coconut palms. Later, as the year comes to its end, the sounds of Cicadas will cease and a new generation will be starting the first of their many years beneath the ground. 

© R. Attrill 2000