Temporal range: Late Permian–Recent
The grasshopper is an insect of the suborder Caelifera in the order Orthoptera, sometimes referred to as the short-horned grasshopper to distinguish it from katydids, or bush crickets. Grasshopper species which change color and behavior at high population densities are called locusts.
- 1 Characteristics
- 2 Diversity and range
- 3 Biology
- 4 Other information
- 5 See also
- 6 References
- 7 Further reading
- 8 External links
Grasshoppers have antennae that are generally shorter than their body and short ovipositors. They also have pinchers or mandibles that cut and tear off food. Those species that make easily heard noises usually do so by rubbing the hind femurs against the forewings or abdomen (stridulation), or by snapping the wings in flight. Tympana, if present, are on the sides of the first abdominal segment. The hind femora are typically long and strong, fitted for leaping. Generally they are winged, but hind wings are membranous while front wings (tegmina) are coriaceous and not fit for flight. Females are normally larger than males, with short ovipositors. Males have a single unpaired plate at the end of the abdomen. Females have two pairs of valves (triangles) at the end of the abdomen used to dig in sand during egg laying.
They are easily confused with the other sub-order of Orthoptera, Ensifera (crickets), but are different in many aspects, such as the number of segments in their antennae and structure of the ovipositor, as well as the location of the tympana and modes of sound production. Ensiferans have antennae with at least 20–24 segments, and caeliferans have fewer. In evolutionary terms, the split between the Caelifera and the Ensifera is no more recent than the Permo-Triassic boundary (Zeuner 1939).
Diversity and range
Recent estimates (Kevan 1982; Günther, 1980, 1992; Otte 1994–1995; subsequent literature) indicate some 2,400 valid Caeliferan genera and about 11,000 valid species described to date. Many undescribed species exist, especially in tropical wet forests. The Caelifera are predominantly tropical.
Diet and digestion
Grasshoppers prefer to eat grasses, leaves and cereal crops, but many grasshoppers are omnivorous. The majority of grasshoppers are polyphagous. Many will eat from multiple host plants in one day, while some prefer to rely on the same host plant. Only one[specify] of the 8000 species of grasshopper is monophagous and will only eat a single species of plant.
The digestive system of insects includes a foregut (stomodaeum, the mouth region), a midgut (mesenteron), and a hindgut (proctodaeum, the anal region). The mouth is distinct due to the presence of a mandible and salivary glands. The mandible can chew food very slightly and start mechanical digestion. Salivary glands (occur in buccal cavity) chemically digest the carbohydrates in the grasses and similar foods they eat. The buccal cavity continues with pharynx, esophagus and crop. The crop has the ability to hold food. From the crop, food enters the gizzard, which has tooth-like features in it. From there, food enters the stomach. In the stomach, digestive enzymes mix with the food to break it down. These enzymes originate from the gastric caeca surrounding the stomach. This leads to the malpighian tubules. These are the chief excretion organs. The hindgut includes intestine parts (including the ileum and rectum), and exits through the anus. Most food is handled in the midgut, but some food residue as well as waste products from the malpighian tubules are managed in the hindgut. These waste products consist mainly of uric acid, urea and amino acids, and are normally converted into dry pellets before being disposed.
The salivary glands and midgut secrete digestive enzymes. The midgut secretes protease, lipase, amylase, and invertase, among other enzymes. The particular ones secreted vary with the different diets of grasshoppers.
Grasshoppers have a nervous system that is fairly typical for an insect. The central nervous system (CNS) consists of a ventral nerve cord containing a chain of ganglia, connected together longitudinally by bilaterally-paired bundles of axons called inter-ganglionic connectives. A ganglion is a "package" of nerve cells, and in general there is one ganglion in each segment, although in some cases several adjacent ganglia fuse together to form a larger package. The nerves within each ganglion control what is going on in its containing segment(s), and the connectives coordinate activity between segments. The ganglion at the front of the animal forms the brain, and this is enlarged because it contains enhanced neural machinery for processing sensory information, particularly that coming from the eyes and antennae. In addition to this major somatic component of the CNS there is a series of small ganglia known as the visceral nervous system, and these control a variety of functions involving parts of the gut, respiratory and hormonal systems.
Grasshoppers have an extensive set of external sense organs. On the head there are a pair of large compound eyes and three simple eyes (ocelli), a pair of antennae containing olfactory (smell) and touch receptors, and mouthparts containing gustatory (taste) receptors. At the front end of the abdomen there is a pair of tympanal organs for sound reception. There are numerous fine hairs covering the whole body that act as mechanoreceptors (touch and wind sensors), and these are most dense on the antennae, palps (part of the mouth), and cerci (near the posterior). There are special receptors (campaniform sensillae) embedded in the cuticle that sense pressure and cuticle distortion. There are also numerous internal sense organs, many of which are specialized to detect position and movement about the joints of the exoskeleton (chordotonal organs). The receptors convey information to the CNS through sensory neurons, and most of these have their cell bodies located in the periphery near the receptor site itself.
Circulation and respiration
As with insects and other organisms possessing open circulatory systems, most body cavities and appendages contain the blood-like substance hemolymph, which in grasshoppers tends to appear green-ish when exposed to open air. The dorsal vessel is the exception to the grasshopper's open circulation and extends from the head through the thorax to the hind end. It is a continuous tube with two regions: the heart, which is restricted to the abdomen; and the aorta, which extends from the heart to the head through the thorax. Haemolymph is pumped forward from the hind end and the sides of the body through a series of valved chambers, each of which contains a pair of lateral openings (ostia). The haemolymph continues to the aorta and is discharged through the front of the head. Accessory pumps carry haemolymph through the wing veins and along the legs and antennae before it flows back to the abdomen. This haemolymph circulates nutrients through the body and carries metabolic wastes to the malphighian tubes to be excreted. Respiration is performed using tracheae, air-filled tubes, which open at the surfaces of the thorax and abdomen through pairs of spiracles. The spiracle valves only open to allow oxygen and carbon dioxide exchange. The tracheoles, found at the end of the tracheal tubes, are insinuated between cells and carry oxygen throughout the body. (For more information on respiration, see Insect.)
Grasshoppers jump by extending their large back legs and pushing against the substrate (the ground, a twig, a blade of grass or whatever else they are standing on); the reaction force propels them into the air. They jump for several reasons; to escape from a predator, to launch themselves for flight, or simply to move from place to place. For the escape jump in particular there is strong selective pressure to maximize take-off velocity, since this determines the range. This means that the legs must thrust against the ground with both high force and a high velocity of movement. However, a fundamental property of muscle is that it cannot contract with both high force and high velocity, which seems like a problem. Grasshoppers overcome this apparent contradiction by using a catapult mechanism to amplify the mechanical power produced by their muscles.
The jump is a three-stage process. First, the grasshopper fully flexes the lower part of the leg (tibia) against the upper part (femur) by activating the flexor tibiae muscle (the back legs of the immature grasshopper in the top photograph are in this preparatory position). Second, there is a period of co-contraction in which force builds up in the large, pennate extensor tibiae muscle, but the tibia is kept flexed by the simultaneous contraction of the flexor tibiae muscle. The extensor muscle is much stronger than the flexor muscle, but the latter is aided by specializations in the joint that give it a large effective mechanical advantage over the former when the tibia is fully flexed. Co-contraction can last for up to half a second, and during this period the extensor muscle shortens and stores elastic strain energy by distorting stiff cuticular structures in the leg. The extensor muscle contraction is quite slow (almost isometric), which allows it to develop high force (up to 14 N in the desert locust), but because it is slow the energy is stored at low power. The third stage of the jump is the trigger relaxation of the flexor muscle, which releases the tibia from the flexed position. The subsequent rapid tibial extension is driven mainly by the relaxation of the elastic structures, rather than by further shortening of the extensor muscle. In this way the stiff cuticle acts like the elastic of a catapult, or the bow of a bow-and-arrow. Energy is put into the store at low power by slow but strong muscle contraction, and retrieved from the store at high power by rapid relaxation of the mechanical elastic structures.
In certain countries, grasshoppers are eaten as a good source of protein. In southern Mexico for example, chapulines are regarded for their high content of protein, minerals and vitamins. They are usually collected at dusk, using lamps or electric lighting, in sweep nets. Sometimes they are placed in water for 24 hours, after which they can be boiled or eaten raw, sun-dried, fried, flavoured with spices, such as garlic, onions, chile, drenched in lime, and used in soup or as a filling for various dishes. They are abundant in Central and Southern Mexican food and street markets.
In some countries in Africa, grasshoppers are an important food source, as are other insects, adding proteins and fats to the daily diet, especially in times of food crisis. They are often used in soup. The "grasshoppers" eaten in Uganda and neighbouring areas are called nsenene, but they are in fact bush crickets, also called katydids.
In some countries in the Middle East, grasshoppers are boiled in hot water with salt, left in the sun to dry then eaten as snacks.
Many insects eat grasshoppers including many types of ants, like those in the genus Crematogaster.
Locusts are several species of short-horned grasshoppers of the family Acrididae that sometimes form very large groups (swarms); these can be highly destructive and migrate in a more or less coordinated way. Thus, these grasshoppers have solitary and gregarious (swarm) phases. Locust swarms can cause massive damage to crops. Important locust species include Schistocerca gregaria and Locusta migratoria in Africa and the Middle East, and Schistocerca piceifrons in tropical Mexico and Central America (Mesoamerica). Other grasshoppers important as pests (which, unlike true locusts, do not change color when they form swarms) include Melanoplus species (like M. bivittatus, M. femurrubrum and M. differentialis) and Camnula pellucida in North America; the Romalea guttata (lubber grasshopper), Brachystola magna, and Sphenarium purpurascens in northern and central Mexico; species of Rhammatocerus in South America; and the Oedaleus senegalensis (Senegalese grasshopper) and the Zonocerus variegatus (variegated grasshopper) in Africa.
The coloring of different species of grasshopper are often dependent on environment. Many species are adapted to green fields and forests, and blend in well there to avoid predators. Others have adapted to drier, sandy environments and blend in well with the colors of dry dirt and sand.
On the American Great Plains
During drought years on the Great Plains during the first half of the 1890s, great clouds of grasshoppers became an uncontrollable pest. They destroyed gardens, crops, grass, and harness. The grasshoppers "cleaned the pastures and fields over which they passed until they were as bare as a floor. They ate harness, coats, or anything that was left outside," reported J. L. Francis of Briscoe County, Texas. N. M. Akeson of Hale County, Texas, recalled that the grasshoppers once ate his mail, which he lost on the trail, only to find it in ruins when he came to retrieve it. According to Mrs. Fred Scott of Swisher County, Texas, the grasshoppers "swarmed toward the southwest and ... in such great numbers that they obscured the sun."
In popular culture
- Aesop (620–560 BC), a slave and story-teller who lived in Ancient Greece, told a tale called The Ant and the Grasshopper. In this tale, the ant worked hard preparing his shelter and stores of food all summer, while the grasshopper played. When winter came, the ant was prepared, but the grasshopper has no shelter or food. He begs to enter the ant's house, but the ant refuses and the grasshopper starves.
- Canadian philosopher Bernard Suits contrasts Aesop's grasshopper (the "hero of a cautionary tale") with his own account of the same story. In Suits' version, the grasshopper is "the exemplification of the life most worth living." The Suits grasshopper is focused on game-playing, and Suits' book on the grasshopper is now well known for the definition of "game" it provides: "the voluntary overcoming of unnecessary obstacles." 
- As a result of the popularity of Aesop's fable in Western culture, various other human weaknesses besides improvidence began to be identified with the grasshopper's behaviour. So an unfaithful woman (hopping from man to man) became known as 'a grasshopper'. Portrayal of such women occurs for example in Poprygunya, a short story written in 1892 by Anton Chekhov, and in Jerry Paris' 1969 film "The Grasshopper".
- Those who are unable to keep a single subject in focus but keep bringing in inappropriate associations (hopping from one thing to another) are said to have 'a grasshopper mind'.
- Partly as a result of this, 'grasshopper' has lately come to refer to a person who has much to learn. Its use originated from the television show Kung Fu (1972–1975). Caine, the young student, portrayed by Radames Pera, is receiving instruction from his Master Po (portrayed by Keye Luke) who nicknames his student "Grasshopper" as a term of endearment.
- In the 1998 movie A Bug's Life, the heroes are the members of an ant colony, and the lead villain and his henchmen are grasshoppers. In an apparent homage to the Aesop fable, The Ant and the Grasshopper, the lead villain is eaten by a bird.
- The Japanese superhero franchise "Kamen Rider" originally had a grasshopper motif, with a grasshopper based helmet and costume. Latter motifs were either not or close to being a grasshopper, although most features of the original superhero remains such as the "compound eyes".
- Insect Design – Insect Mouth Parts. National Park Service
- Zeuner, F. E. (1939). Fossil Orthoptera Ensifera. London: British Museum Natural History.
- O'Neill, Kevin M.; Woods, Stephen A.; Streett, Douglas A. (1997). "Grasshopper (Orthoptera: Acrididae) Foraging on Grasshopper Feces: Observational and Rubidium-Labeling Studies". Environmental Entomology 26 (6): 1224–1231.
- Davidowitz, Goggy. Grasshoppers. Arizona-Sonora Desert Museum
- Burrows, M. (1996) The neurobiology of an insect brain. Oxford University Press, Oxford. ISBN 0198523440
- Mechanical power is force x velocity
- Burrows, M. (1995). "Motor patterns during kicking movements in the locust". Journal of Comparative Physiology A 176 (3): 289–305. doi:10.1007/BF00219055. PMID 7707268.
- Heitler, W.J. (1977). "The locust jump III. Structural specializations of the metathoracic tibiae". Journal of Experimental Biology 67: 29–36.
- Bennet-Clark, H. C. (1975). "The energetics of the jump of the locust Schistocerca gregaria". The Journal of experimental biology 63 (1): 53–83. PMID 1159370.
- Bizarre Foods with Andrew Zimmern aired on the Travel Channel 27 April 2008.
- King, Bes Sie (December 23, 2009). "Snack on grasshoppers". Ny Food Chain (New York: Columbia University Graduate School of Journalism). Retrieved February 24, 2015.
- Sheffy, Lester Fields (1950). The Life and Times of Timothy Dwight Hobart, 1855–1935: Colonization of West Texas. Canyon, Texas: Panhandle-Plains Historical Society. pp. 131–132.
- Suits, Bernard (2005) The Grasshopper: Games, Life and Utopia. Broadview Press. ISBN 1770480110
- Firefly Encyclopedia of Insects and Spiders, edited by Christopher O'Toole, ISBN 1-55297-612-2, 2002
- Grasshopper species to watch for on the Canadian Prairies and Northern Great Plains, Dan Johnson
- Grasshoppers: Life Cycle, Damage Assessment and Management Strategy, Govt. of Alberta
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- American grasshopper on the UF / IFAS Featured Creatures Web site
- A grasshopper plague is at hand in U.S. | Newsdesk.org (March 30, 2010)
- How Grasshoppers Jump