Cicada

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A cicada also known as a "jar fly" is an insect of the order Hemiptera, suborder Auchenorrhyncha, in the superfamily Cicadoidea, with large eyes wide apart on the head and usually transparent, well-veined wings. There are approximately 2,500 species of cicada around the globe, and many remain unclassified. Cicadas live in temperate to tropical climates where they are one of the most widely recognized of all insects, mainly due to their large size and remarkable (and often inescapable) acoustic talents. Cicadas are sometimes incorrectly called "locusts"^[1], although they are unrelated to true locusts, which are a kind of grasshopper. Cicadas are related to leafhoppers and spittlebugs. In parts of the southern Appalachian Mountains in the United States they are known as "dry flies" because of the dry shell they leave behind.

Cicadas do not bite or sting, are benign to humans, and are not considered a pest. Many people around the world regularly complement their standard diet with cicadas: the female is prized for eating as it is meatier. Cicadas have been eaten (or are still eaten) in Ancient Greece, China, Malaysia, Burma, Australia, Latin America and the Congo. Cicadas are employed in the traditional medicines of China and Japan for hearing-related matters.^{[citation needed]}

The word cicada is a direct derivation of the Latin cicada. In classical Greek it was called a tettix, and in modern Greek tzitzikas.

[edit] Taxonomy

Cicadas are arranged into two families: Tettigarctidae (treated elsewhere) and Cicadidae. There are two extant species of Tettigarctidae, one in southern Australia, and the other in Tasmania. The family Cicadidae is subdivided into the subfamilies Tettigadinae, Cicadinae and Cicadettinae, and they occur on all continents except Antarctica.

The largest cicadas are in the genera Pomponia and Tacua. There are some 200 species in 38 genera in Australia, about 450 species in Africa, about 100 in the Palaearctic and exactly one species in England, the New Forest cicada, Melampsalta montana, which is widely distributed throughout Europe. There are about 150 species in South Africa.

Most of the North American species are in the genus Tibicen - the annual or dog-day cicadas (named after the "Dog Days" because they emerge in late July and August ^[1] ). The best-known North American genus is Magicicada, however. These periodical cicadas have an extremely long life cycle of 13 or 17 years and emerge in large numbers ^[1] . Another American species is the Apache cicada, Diceroprocta apache.

38 species from five genera populate New Zealand, and all of the species are endemic to New Zealand and the surrounding islands (Norfolk Island, New Caledonia).

There are several kinds of cicadas in Japan. Called "semi", they sing at all times of day and night and can be heard through walls.

[edit] Description

Adult cicadas, sometimes called imagines, are usually between 2 and 5 cm (1 to 2 inches) long, although there are some tropical species that reach 15 cm (6 in), e.g. Pomponia imperatoria from Malaysia. Cicadas have prominent eyes set wide apart on the sides of the head, short antennae protruding between or in front of the eyes, and membranous front wings. Desert cicadas are also one of the few insects known to cool themselves by sweating^{[citation needed]}, while many other cicadas can raise their body temperatures voluntarily to around 40 °C (104°F), even when the air temperature is only 18°C (65°F)^{[citation needed]}.

Male cicadas have loud noisemakers called "timbals" on the sides of the abdominal base. Their "singing" is not stridulation as in many other familiar sound-producing insects like crickets (where two structures are rubbed against one another): the timbals are regions of the exoskeleton that are modified to form a complex membrane with thin, membranous portions and thickened "ribs". They rapidly vibrate these membranes with strong muscles, and enlarged chambers derived from the tracheae make their body serve as a resonance chamber, greatly amplifying the sound. Some cicadas produce sounds louder than 106 dB (SPL)^{[citation needed]}, among the loudest of all insect-produced sounds. They modulate their noise by wiggling their abdomens toward and away from the tree that they are on. Additionally, each species has its own distinctive song ^[1] .

Only males produce the cicadas' distinctive sound. Both sexes, however, have tympana, which are membranous structures used to detect sounds; thus, the cicadas' equivalent of ears. Adult cicadas have a sideways-ridged plate where the mouth is in normal insects.

[edit] Cicada song

Cicadas are the loudest and most efficient sound-producing insects in the world^{[citation needed]}. Conversely, some small species have songs so high in pitch that the noise is inaudible to humans^{[citation needed]}. Only the males resound as a mating ritual to attract a female and many cicada species tend to gather when calling which increases the total volume of noise. Species have different mating songs to ensure they attract the appropriate mate.

Cicadas are unique in sound-producing insects in that they have a musical drum in their abdomen. The organs that produce sound are ‘timbals' ~ paired membranes that are ribbed and located at the abdominal base. Contracting the internal tymbal muscles yield a pulse of sound as the timbals buckle inwards. As these muscles relax, the timbals return to their original position. The interior of the male abdomen is substantially hollow to amplify the resonance of the sound. The song intensity of the louder cicadas acts as an effective bird repellent^{[citation needed]}. Males of many species tend to gather which creates a greater sound intensity and engenders protection from avian predators.

In addition to the mating song, many species also have a distinct distress call, usually a somewhat broken and erratic sound emitted when an individual is seized. A number of species also have a courtship song, which is often a quieter call and is produced after a female has been drawn by the calling song.

The song of the cicada is a favorite sound effect used by filmmakers and animators as a means of representing silence, pathos, and the great outdoors.

[edit] Life cycle

After mating, the female cuts slits into the bark of a twig, and into these she deposits her eggs. She may do so repeatedly, until she has laid several hundred eggs. When the eggs hatch, the newborn nymphs drop to the ground, where they burrow. Most cicadas go through a life cycle that lasts from two to five years. Some species have much longer life cycles, e.g. the Magicicada goes through a 17- or occasionally 13-year life cycle. These long life cycles are an adaptation to predators such as the cicada killer wasp and praying mantis, as a predator could not regularly fall into synchrony with the cicadas. Both 13 and 17 are prime numbers, so while a cicada with a 15-year life cycle could be preyed upon by a predator with a 3- or 5-year life cycle, the 13- and 17-year cycles allow them to stop the predators falling into step.^{[citation needed]}

The insects spend most of the time that they are underground as nymphs at depths ranging from about 30 cm (1 ft) up to 2.5 m (about 8½ ft). The nymphs feed on root juice and have strong front legs for digging.

In the final nymphal instar, they construct an exit tunnel to the surface and emerge. They then moult (shed their skins), on a nearby plant for the last time and emerge as an adult. The abandoned skins remain, still clinging to the bark of trees.

[edit] Cicadas in Australia

Around 220 cicada species have been identified in Australia many of which go by fanciful common names such as: Cherry Nose, Brown Baker, Red Eye (psaltoda moerens), Green Grocer/Green Monday^[2], Yellow Monday, Whisky Drinker, Double Drummer(Thopha saccata), and Black Prince. The Australian green grocer, Cyclochila australasiae, is amongst the loudest insects in the world.

Being principally tropical insects, most Australian species are found in the northern states. However, cicadas occur in almost every part of Australia: the hot wet tropical north; Tasmanian snowfields; Victorian beaches and sand dunes such as Torquay and deserts. According to Max Moulds of the Australian Museum in Sydney: "the 'green grocer' is unusual in its ability to adapt perfectly to the urbanized environment." Cicada sounds are a defining quality of Melbourne and Sydney.

Cicadas inhabit both native and exotic plants including tall trees, coastal mangroves, suburban lawns and desert shrubbery. The great variety of flora and climatic variation found in north-eastern Queensland results in its being the richest region for the spread of different species. The area of greatest species diversity is a 100 km (60 mi) wide region centered around Cairns. In some areas they are preyed on by the Cicada-hunter (Exeirus lateritius) which stings and stuns cicadas high in the trees, making them drop to the ground where the Cicada-hunter mounts and rides them, pushing with its hind-legs, sometimes over a distance of a hundred yards, till they can be shoved down into its burrow, where the numb Cicada is placed onto one of many shelves in a 'catacomb', to form the food-stock for the wasp grub that grows out of the egg deposited there ^[3].

[edit] Genera

[edit] Gallery