It is evening, in the deepest of the Kakamega rain forest. We have been watching birds that land here from the Eurasian region, to roost and escape the winter season.
The day has been noisy with all the birds singing in their own specific language, forming a cacophony of sounds, quite unpleasant to those unused to the world of nature.
As we return to the Rondo Retreat Centre to review the day’s work and have a well-deserved rest, the sun is setting on the horizon, throwing grotesque shadows of the tall trees on the garden of the centre. The sounds of the wild seem to increase as the rainforest whispers the invitations to the darkness to come in.
When darkness accepts the invitation to the forest, everything within metres vanishes into nothingness. Within no time, the awful noises that had made the forest sound like the devils ‘workshop’, goes down in volume and finally settles down to only a whisper.
Save for only a continuous very high pitched metallic sound that seems to be coming from scratching a metal pipe with a folk. Or better still, the sound of very many bottles being dropped from a height and falling on a hard surface, one by one but in frequent succession. That was the sound of a cricket.
Crickets are small insects related to grasshoppers. They are mostly confused with young or juvenile grasshoppers because they also have similar jumping hind legs and similar antennas.
The body structure of a cricket closely resembles that of a juvenile grasshopper. But they are two different species of insects with different characteristic.
Grasshoppers are diurnal while crickets tend to be nocturnal. There are over 900 species of crickets in the world. Very few of them are harmful to humans. Those that may be harmful are those who can bite. But even the bite is not serious enough to cause major damage to the skin.
The sound made by the cricket is called chirping. In a more technical language, the sound is known as stridulating. Just like in most animals, the males are the ones who stridulate, or chirp, although in some species of crickets, some females may also chirp especially for the purpose of answering a male chirping as a nuptial call. (Nuptial call can also be referred to as mating call.) It is believed mythically that the chirping sound of a cricket is made by rubbing the hind legs together.
This was probably true from what was observed by early researchers who saw a blurry of activities in the rear of the insect where the noise emanated from.
But now, with the emergence of super fast digital photography and high definition filming, researchers have found out that the sound is not from rubbing feet together, but rather vibrating wings. On the lower side of each wing, there is a stridulatory organ. A large serrated (toothed) vein, running along the lower edge of the wing.
When the cricket wants to make the noise, he simply runs the left wing over the serrated vein on the lower part of the right wing very fast and voila!
The sound is made. If he gets bored by the pitch, he tries the opposite side of the wing. During the chirping, one wing is held up like a sail to amplify the sound.
It is worth noting that the chirping of the crickets is usually a message to others of similar species. The frequency of the chirping changes with the temperatures of the day.
When it is hot, the chirping is faster. When it is cold, the chirping rate is slower. The pitch and the volume of the sound changes with the message. When the male is calling for a mate, the sound is of a lower pitch and soft volume.
When it is chirping in close proximity to another male, the pitch is very high and aggressive, mainly to advertise superiority over the mating rites.
It is not well known whether other insects hear the chirping of crickets. The cricket themselves have what we call the tympanic membrane which is located near the knee joint of the front legs which they use to detect sounds from themselves.
Lack of similar membranes in other related insects make us believe that only crickets can understand their own language from the chirping sounds.