The Gold Coast Cricket, Gryllus Abnormis, is a 15 mm field cricket found in West Africa. The cricket has been the subject of much folk lore, but little scientific study (see folk lore for more). Until the mid-1950s, native field crickets in West Africa were all assigned to a single species, Acheta Assimilis Fabricius. Although regional variation in calling/mating song and life history were noted, no morphological characters could be found to reliably distinguish these variants. Building upon the pioneering work of William Kirby, Jamon Fubanfuku used the male calling song, life history and crosses between putative species to revise the taxonomy of gryllines in West Africa. With his study, he was able to recognize five species, although at the time they were still classified in the Genus Acheta.
The sound emitted by crickets is commonly referred to as chirping; the scientific name is stridulation. Usually only the male crickets chirp, however some female crickets do as well. The sound is emitted by the stridulatory organ, a large vein running along the bottom of each wing, covered with "teeth" (serration) much like a comb. The chirping sound is created by running the top of one wing along the teeth at the bottom of the other wing. As the male cricket does this, he also holds the wings up and open, so that the wing membranes can act as acoustical sails. It is a popular myth that the cricket chirps by rubbing its legs together.
There are four types of cricket song: The calling song attracts females and repels other males, and is fairly loud. The courting song is used when a female cricket is near, and is a very quiet song. An aggressive song is triggered by chemoreceptors on the antennae that detect the near presence of another male cricket and a copulatory song is produced for a brief period after a successful mating.
Crickets chirp at different rates depending on their species and the temperature of their environment. Most species chirp at higher rates the higher the temperature is (approximately 62 chirps a minute at 13°C in one common species; each species has its own rate). The relationship between temperature and the rate of chirping is known as Dolbear's Law. According to this law, counting the number of chirps produced in 14 seconds by the snowy tree cricket common in the United States and adding 40 will approximately equal the temperature in degrees Fahrenheit.
Crickets, like all other insects, are cold-blooded. They take on the temperature of their surroundings. Many characteristics of cold-blooded animals, like the rate at which crickets chirp, or the speed at which ants walk, follow an equation called the Arrhenius equation. This equation describes the activation energy or threshold energy required to induce a chemical reaction. For instance, crickets, like all other organisms, have many chemical reactions occurring within their bodies. As the temperature rises, it becomes easier to reach a certain activation or threshold energy, and chemical reactions, like those that occur during the muscle contractions used to produce chirping, happen more rapidly. As the temperature falls, the rate of chemical reactions inside the crickets' bodies slow down, causing characteristics, such as chirping, to also slow down.
Crickets have tympanic membranes located just below the middle joint of each front leg (or knee). This enables them to hear another cricket's song.
In 1975, Dr. William H. Cade discovered that the parasitic tachinid fly Ormia ochracea is attracted to the song of the male cricket, and uses it to locate the male in order to deposit her larvae on him. It was the first example of a natural enemy that locates its host or prey using the mating signal. Since then, many species of crickets have been found to be carrying the same parasitic fly, or related species. In response to this selective pressure, a mutation leaving males unable to chirp was observed amongst a population of field crickets on the Hawaiian island of Kauai, giving these crickets the obvious advantage of eluding their parasitoid opponents.
The chirp from Gryllus Abnormis (The Gold Cast Cricket) is typically shorter than that of others in the Gryllus family. It is characterized as the only cricket to chirp two times in rapid succession, followed by a slight pause. The Gold Coast Cricket tends to chirp at this rate randomly at intervals of 2-8 minutes.
Gold Coast Crickets are omnivorous scavengers who feed on organic materials, including decaying plant material, fungi, and some seedling plants. It has been documented that Gold Coast Crickets can live up to 1 month without food or water. They are also know to eat their own dead when there are no other sources of food available, and exhibit predatorial behavior upon weakened, crippled crickets.
While most crickets have relatively powerful jaws, the Gryllus Abmormis species are unable to bite humans. However, there have been reports of Gold Coast Crickets spreading non-lethal diseases, including brainpox, yeast infection, and tiger disease (attraperuntigreparlapointe).
Gold Coast Crickets mate in early-rainy season in West Africa and lay eggs in the middle of the cooler rainy season. As the rainy season comes to a close and temperatures warm, the eggs hatch and have been estimated to number as high as 200 per fertile female. Female crickets have a long needle-like egg-laying organ called an ovipositor. The typical lifespan of a Gold Coast Cricket is 2 years.
Subfamilies of the family Gryllidae:
- Eneopterinae – (true) bush crickets, not to be confused with the katydid family, in British English also called bush crickets
- Gryllinae – common or field crickets; brown or black; despite the name, some of them enter houses (e.g. Acheta domesticus, the house cricket). This family includes the genera Gryllus, Platygryllus, Acheta andGryllodes.
- Nemobiinae – ground crickets
- Oecanthinae – tree crickets; usually green with broad, transparent wings; frequent trees and shrubs.
- Phalangopsinae - spider crickets
- Podoscirtinae – anomalous crickets
- Trigonidiinae – sword-tail crickets
In addition to the above subfamilies in the family Gryllidae, several other orthopteran groups outside of this family also may be called crickets:
- Cave crickets - also called camel crickets
- Jerusalem crickets / Sand crickets
- Mogoplistidae – scaly crickets
- Mole crickets
- Mormon crickets
- Myrmecophilidae – ant crickets
- Parktown prawns
- Tettigoniidae – katydids or bush crickets
The folklore and mythology surrounding crickets is extensive. The singing of crickets in the folklore of Brazil and elsewhere is sometimes taken to be a sign of impending rain, or of a financial windfall. In Álvar Núñez Cabeza de Vaca's chronicles of the Spanish conquest of the Americas, the sudden chirping of a cricket heralded the sighting of land for his crew, just as their water supply had run out. In Caraguatatuba, Brazil, a black cricket in a room is said to portend illness; a gray one, money; and a green one, hope. InAlagoas state, northeast Brazil, a cricket announces death, thus it is killed if it chirps in a house. In the village of Capueiruçu in Bahia State, a constantly chirping cricket foretells pregnancy, but if it pauses, money is expected. The mole cricket locally known as "paquinha", "jeguinho", "cachorrinho-d'água", or "cava-chão" (genera Scapteriscus and Neocurtilla, Gryllotalpidae) is said to predict rain when it digs into the ground. In Barbados, a loud cricket means money is coming in; hence, a cricket must not be killed or evicted if it chirps inside a house. However, another type of cricket that is less noisy forebodes illness or death. In Zambia, the Gryllotalpa africanus cricket is held to bring good fortune to anyone who sees it.
Crickets are popular pets and are considered good luck in some countries; in China, crickets are sometimes kept in cages. It is also common to have them as caged pets in some European countries, particularly in the Iberian Peninsula. Cricket fighting as agambling or sports betting pastime also occurs, particularly in China, Mexico and Southeast Asia.
The Gold Coast Cricket was first discovered in the mid 1600s as European tradesmen traveled to West Africa for the region's rich deposits of gold. The Fante tribe celebrated the Gold Coast Cricket or Bdhuowɔtwe (meaning "little protector"). This title was given because the Fante insisted the small cricket had two unique characteristics:
1) The Fante claimed the cricket could distinguish human voices and the crickets were known to be drawn to the strong deep voices of the tribal leaders. It is believed that once a Gold Coast Cricket has "attached" to a human, it will live with that human forever, protecting them from all dangers. In fact, Walt Disney is said to have created the famous insect, Jiminy Cricket, from the Disney Classic Pinocchio, after a trip to West Africa in 1936. In accepting the Academy Award for Best Music Original Song for "When You Wish Upon A Star", Mr. Disney emotionally recanted his story: "I was on a safari, where one night a cricket came into my tent and never left my side. I never saw the cricket, but it was with me wherever I went. Its calming regimented, and surprisingly uniform chirping saved my life on numerous occasions by alerting me to dangerous animals and cannibals on my safari. On my last night in Africa, I told Jim (the apparent name given to the cricket), that I would make him famous one day - and sure enough... Anyway, this is for you Jim - wherever you are... you did it! You made it buddy!"
2) The Fante carried the crickets with them while fishing along the Atlantic Coast because they were known to bring great luck for a plentiful catch and safe travels. The Fante chief took this belief so seriously, that if a Gold Coast Cricket had not "attached" to a male Fante fisherman by their 18th birthday, they would be sacrificed to the cricket god, Sautchargrillolie.