Cicada

As soon as I saw an exuvia of cicada on one of the tree trunks in our garden, I knew we were in for an ear splitting noise of cicadas. Peak of the summer every year I get a lots of these cicadas in our garden. Exuviae is the remains of an exoskeleton that are left after insect, crustacean or arachnid have moulted. Within a week my surrounding was buzzing with cicada sounds. The cicada I had seen that day belongs to the Dundubia species. Its name is derived from Sanskrit word Dundubi which means drum. The first two photographs here are results of stacking several closeup photos taken using Canon EOS 5D Mark III and Canon EF 100mm f/2.8L Macro IS USM to get increased depth of field without flash. I wanted to use natural light and get slow shutter speed photos using tripod and then stack them together. Even with f/11 the depth of field I had obtained in an individual picture was very shallow. This is the result of being so close to the subject. I have used Zerene Stacker program to stack them. Other three pictures are normal closeups.

Cicadas are insects in the order Hemiptera, suborder Auchenorrhyncha.Their eyes are prominent, though not especially large, and set wide apart on the anterior lateral corners of the frons. The wings are well-developed, with conspicuous veins; in some species the wing membranes are wholly transparent, whereas in many others the proximal parts of the wings are clouded or opaque and some have no significantly clear areas on their wings at all. About 2,500 species of cicada have been described, and many remain to be described. Cicadas live in temperate-to-tropical climates where they are among the most-widely recognized of all insects, mainly due to their large size and unique sound. Cicadas are related to leafhoppers and spittlebugs. Cicadas differ from related groups in having three ocelli (simple eyes) located between the two large compound eyes. Other auchenorrhynchous Hemiptera have only two ocelli.

Male cicadas have loud noisemakers called “tymbals” on the sides of the abdominal base. Their “singing” is not the stridulation (where one structure is rubbed against another) of many other familiar sound-producing insects like crickets: the tymbals are regions of the exoskeleton that are modified to form a complex membrane with thin, membranous portions and thickened “ribs”. Contracting the internal tymbal muscles produces a clicking sound as the tymbals buckle inwards. As these muscles relax, the tymbals return to their original position producing another click. The interior of the male abdomen is substantially hollow to amplify the resonance of the sound. A cicada rapidly vibrates these membranes, and enlarged chambers derived from the tracheae make its body serve as a resonance chamber, greatly amplifying the sound. The cicada modulates the sound by positioning its abdomen toward or away from the substrate. Additionally, each species has its own distinctive “song”.

Although only males produce the cicadas’ distinctive sound, both sexes have tympana, which are membranous structures used to detect sounds and thus the cicadas’ equivalent of ears. Males can disable their own tympana while calling. Some cicadas produce sounds up to 120 dB among the loudest of all insect-produced sounds. It is technically loud enough to cause permanent hearing loss in humans, should the cicada sing just outside the listener’s ear. Conversely, some small species have songs so high in pitch that the noise is inaudible to humans. Species have different mating songs to ensure they attract the appropriate mate. It can be difficult to determine from which direction(s) a cicada song is coming, because the low pitch carries well and because it may, in fact, be coming from many directions at once, as cicadas in various trees may make noise in unison. 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.

Cicada nymphs differ from the immatures of other Auchenorrhyncha in having fossorial forelegs (modified for digging). Female cicadas generally deposit their eggs in twigs or branches of woody host plants, or on grasses. Soon after hatching, nymphs drop to the ground and burrow into the soil where they feed on roots. Like froghoppers, cicadas feed mostly on plant xylem. The subterranean nymphs develop relatively slowly, taking from a few years to as long as 13 or 17 years in the periodical cicadas of North America (genus Magicicada). South Asian species are not that periodical and are seen almost once a year. Mature nymphs emerge from the ground and molt to adults, often leaving their nymphal exuviae on tree trunks. Cicadas are benign to humans under normal circumstances and do not bite or sting in a true sense, but may mistake a person’s arm or other part of their body for a tree or plant limb and attempt to feed. Cicadas have a long proboscis, under their head, which they insert into plant stems in order to feed on sap. You can notice that proboscis in my photos it feeds this Indian Almond Tree. It can be painful if they attempt to pierce a person’s skin with it, but it is unlikely to cause other harm. It is unlikely to be a defensive reaction and is a rare occurrence. It usually only happens when they are allowed to rest on a person’s body for an extended amount of time. Cicadas can cause damage to several cultivated crops, shrubs, and trees, mainly in the form of scarring left on tree branches while the females lay their eggs deep in branches.

The adult insect, known as an imago, is 2 to 5 centimeters in total length in most species, although the largest, Pomponia (Megapomponia) imperatoria, has a head-body length of about 7 centimeters and its wingspan is 18 to 20 centimeters. 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. Some species of desert cicadas such as Diceroprocta apache are unusual among insects in that they have been shown to cool themselves by evaporative cooling, analogous to sweating in mammals. When their temperature rises above about 39°C they suck excess sap from the food plants and extrude the excess water through pores in the tergum, at a modest cost in energy. Such a rapid loss of water can only be sustained by feeding on water rich xylem sap.

Most cicadas go through a life cycle that lasts from two to five years. Some species have much longer life cycles, such as the North American genus, Magicicada, which has a number of distinct “broods” that go through either a 17-year or, in some parts of the world, a 13-year life cycle. These long life cycles perhaps developed as a response to predators, such as the cicada killer wasp and praying mantis. A predator with a shorter life cycle of at least two years could not reliably prey upon the cicadas. Cicadas are commonly eaten by birds, and sometimes by squirrels, but Massospora cicadina a fungal disease is the biggest enemy of cicadas. Another known predator is the cicada killer wasp. Cicada killer wasp (Exeirus lateritius), which stings and stuns cicadas high in the trees, making them drop to the ground where the cicada-hunter mounts and carries them, pushing with its hind legs, sometimes over a distance of a hundred meters, until 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.In eastern Australia, the native freshwater fish Australian bass are keen predators of cicadas that crash-land on the surface of streams. Some species of cicada also have an unusual defense mechanism to protect themselves from predation, known as predator satiation: because so many emerge at once, the number of cicadas in any given area exceeds the amount predators can eat; all available predators are thus satiated, and the remaining cicadas can breed in peace.