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Insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pairs ...
s in the
family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...
Tettigoniidae are commonly called katydids (especially in North America), or bush crickets. They have previously been known as "long-horned grasshoppers". More than 8,000
species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
are known. Part of the suborder
Ensifera Ensifera is a suborder of insects that includes the various types of crickets and their allies including: true crickets, camel crickets, bush crickets or katydids, grigs, weta and Cooloola monsters. This and the suborder Caelifera (grasshop ...
, the Tettigoniidae are the only extant (living) family in the superfamily Tettigonioidea. They are primarily
nocturnal Nocturnality is an animal behavior characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnal meaning the opposite. Nocturnal creatures generally have highly developed sens ...
in habit with strident mating calls. Many species exhibit
mimicry In evolutionary biology, mimicry is an evolved resemblance between an organism and another object, often an organism of another species. Mimicry may evolve between different species, or between individuals of the same species. Often, mimicry f ...
and
camouflage Camouflage is the use of any combination of materials, coloration, or illumination for concealment, either by making animals or objects hard to see, or by disguising them as something else. Examples include the leopard's spotted coat, the ...
, commonly with shapes and colors similar to leaves.


Etymology

The family name Tettigoniidae is derived from the genus ''
Tettigonia ''Tettigonia'' is the type genus of bush crickets belonging to the subfamily Tettigoniinae.Linnaeus, C. (1758). ''Systema Naturae per Regna tria naturae'' (10th ed.) 1: 429. The scientific name ''Tettigonia'' is onomatopoeic and derives from t ...
'', first described by
Carl Linnaeus Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his ennoblement in 1761 as Carl von Linné Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomial nomenclature, the ...
in 1758. In Latin ''tettigonia'' means a kind of small cicada,
leafhopper A leafhopper is the common name for any species from the family Cicadellidae. These minute insects, colloquially known as hoppers, are plant feeders that suck plant sap from grass, shrubs, or trees. Their hind legs are modified for jumping, and a ...
; it is from the Greek τεττιγόνιον ''tettigonion'', the diminutive of the imitative (
onomatopoeic Onomatopoeia is the process of creating a word that phonetically imitates, resembles, or suggests the sound that it describes. Such a word itself is also called an onomatopoeia. Common onomatopoeias include animal noises such as ''oink'', ''m ...
) τέττιξ, ''tettix'',
cicada The cicadas () are a superfamily, the Cicadoidea, of insects in the order Hemiptera (true bugs). They are in the suborder Auchenorrhyncha, along with smaller jumping bugs such as leafhoppers and froghoppers. The superfamily is divided into two ...
. All of these names such as ''tettix'' with repeated sounds are
onomatopoeic Onomatopoeia is the process of creating a word that phonetically imitates, resembles, or suggests the sound that it describes. Such a word itself is also called an onomatopoeia. Common onomatopoeias include animal noises such as ''oink'', ''m ...
, imitating the
stridulation Stridulation is the act of producing sound by rubbing together certain body parts. This behavior is mostly associated with insects, but other animals are known to do this as well, such as a number of species of fish, snakes and spiders. The mech ...
of these insects. The common name ''katydid'' is also onomatopoeic and comes from the particularly loud, three-pulsed song, often rendered "''ka-ty-did''", of the
nominate subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...
of the North American ''
Pterophylla camellifolia ''Pterophylla camellifolia'', the common true katydid, is a common North American insect in the family Tettigoniidae (katydids). Within the Tettigoniidae, it belongs to the subfamily Pseudophyllinae (true katydids). Other common names include ...
'', belonging to the subfamily
Pseudophyllinae The subfamily Pseudophyllinae contains numerous species in the family Tettigoniidae, the katydids or bush crickets. Sometimes called "true katydids", together with the crickets of suborder Ensifera, they form part of the insect order Orthoptera ...
, which are known as "true katydids".


Description and life cycle


Description

Tettigoniids range in size from as small as to as large as . The smaller species typically live in drier or more stressful habitats which may lead to their small size. The small size is associated with greater agility, faster development, and lower nutritional needs. Tettigoniids are tree-living insects that are most commonly heard at night during summer and early fall. Tettigoniids may be distinguished from the
grasshopper Grasshoppers are a group of insects belonging to the suborder Caelifera. They are among what is possibly the most ancient living group of chewing herbivorous insects, dating back to the early Triassic around 250 million years ago. Grasshopp ...
by the length of their filamentous antennae, which may exceed their own body length, while grasshoppers' antennae are always relatively short and thickened.


Life cycle

Eggs are typically oval and may be attached in rows to plants. Where the eggs are deposited relates to the way the
ovipositor The ovipositor is a tube-like organ used by some animals, especially insects, for the laying of eggs. In insects, an ovipositor consists of a maximum of three pairs of appendages. The details and morphology of the ovipositor vary, but typical ...
is formed. It consists of up to three pairs of appendages formed to transmit the egg, to make a place for it, and place it properly. Tettigoniids have either sickle-shaped ovipositors which typically lay eggs in dead or living plant matter, or uniform long ovipositors which lay eggs in grass stems. When tettigoniids hatch, the nymphs often look like small, wingless versions of the adults, but in some species, the nymphs look nothing at all like the adult and rather mimic other species such as
ant Ants are eusocial insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from vespoid wasp ancestors in the Cretaceous period. More than 13,800 of an estimated total of 22 ...
s,
spiders Spiders ( order Araneae) are air-breathing arthropods that have eight legs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude silk. They are the largest order of arachnids and rank seventh in total species dive ...
and
assassin bug The Reduviidae are a large cosmopolitan family of the order Hemiptera (true bugs). Among the Hemiptera and together with the Nabidae almost all species are terrestrial ambush predators: most other predatory Hemiptera are aquatic. The main exampl ...
s, or flowers, to prevent predation. The nymphs remain in a mimic state only until they are large enough to escape predation. Once they complete their last molt (after about 5 successful molts), they are then prepared to mate.


Distribution

Tettigoniids are found on every continent except Antarctica. The vast majority of katydid species live in the
tropical The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...
regions of the world. For example, the Amazon basin rain forest is home to over 2,000 species of katydids. However, katydids are found in the cool, dry temperate regions, as well, with about 255 species in North America.


Classification

The Tettigoniidae are a large family and have been divided into a number of subfamilies: The Copiphorinae were previously considered a subfamily, but are now placed as tribe Copiphorini in the subfamily Conocephalinae. The genus '' Acridoxena'' is now placed in the tribe Acridoxenini of the Mecopodinae (previously its own subfamily, Acridoxeninae).


Extinct taxa

The ''Orthoptera species file'' lists: *† Pseudotettigoniinae (North America, Europe) *†
Rammeinae '' Rammea'' is an extinct genus in the Tettigoniidae Insects in the family Tettigoniidae are commonly called katydids (especially in North America), or bush crickets. They have previously been known as "long-horned grasshoppers". More than 8 ...
(Europe) *†
Tettigoidinae ''Tettigoides'' is an extinct genus of katydids containing a single species, ''Tettigoides pectinata''. It is the only genus and species in the subfamily Tettigoidinae. It is known from Ypresian aged deposits near Dinmore, Queensland, Australia. ...
(Australia) ;Genera ''
incertae sedis ' () or ''problematica'' is a term used for a taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In the system of open nomenclature, uncertainty ...
'' * †'' Locustites'' Heer, 1849: 3 spp. * †'' Locustophanes'' Handlirsch, 1939: †''L. rhipidophorus'' Handlirsch, 1939 * †'' Prophasgonura'' Piton, 1940: †''P. lineatocollis'' Piton, 1940 * †'' Protempusa'' Piton, 1940: †''P. incerta'' Piton, 1940 * †'' Prototettix'' Giebel, 1856: †''P. lithanthraca'' (Goldenberg, 1854) The genus †'' Triassophyllum'' is extinct and may be placed here or in the
Archaeorthoptera The cohort Polyneoptera is a proposed taxonomic ranking for the Orthoptera (grasshoppers, crickets, etc.) and all other Neopteran insects believed to be more closely related to Orthoptera than to any other insect orders. These winged insects, n ...
.


Ecology

The diet of most tettigoniids includes
leaves A leaf (plural, : leaves) is any of the principal appendages of a vascular plant plant stem, stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", wh ...
,
flowers A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechani ...
, bark, and
seed A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiospe ...
s, but many species are exclusively
predator Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...
y, feeding on other
insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pairs ...
s,
snail A snail is, in loose terms, a shelled gastropod. The name is most often applied to land snails, terrestrial pulmonate gastropod molluscs. However, the common name ''snail'' is also used for most of the members of the molluscan class Gastro ...
s, or even small
vertebrate Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, ...
s such as
snake Snakes are elongated, Limbless vertebrate, limbless, carnivore, carnivorous reptiles of the suborder Serpentes . Like all other Squamata, squamates, snakes are ectothermic, amniote vertebrates covered in overlapping Scale (zoology), scales. Ma ...
s and
lizard Lizards are a widespread group of squamate reptiles, with over 7,000 species, ranging across all continents except Antarctica, as well as most oceanic island chains. The group is paraphyletic since it excludes the snakes and Amphisbaenia alt ...
s. Some are also considered pests by commercial crop growers and are sprayed to limit growth, but population densities are usually low, so a large economic impact is rare. Tettigoniids are serious insect pests of
karuka The karuka (''Pandanus julianettii'', also called karuka nut and ''Pandanus'' nut) is a species of tree in the family Pandanaceae and an important regional food crop in New Guinea. The nuts are more nutritious than coconuts, and are so popular ...
(''Pandanus julianettii''). The species '' Segestes gracilis'' and ''
Segestidea montana ''Segestidea montana'' is a species of insect in the family Tettigoniidae Insects in the family Tettigoniidae are commonly called katydids (especially in North America), or bush crickets. They have previously been known as "long-horned grass ...
'' eat the leaves and can sometimes kill trees. Growers will stuff leaves and grass in between the leaves of the crown to keep insects out. By observing the head and mouthparts, where differences can be seen in relation to function, it is possible to determine what type of food the tettigoniids consume. Large tettigoniids can inflict a painful bite or pinch if handled, but seldom break the skin. Some species of bush crickets are consumed by people, such as the ''
nsenene Nsenene is the Luganda name for ''Ruspolia differens'': a bush cricket (a.k.a. katydids or misnamed "long-horned grasshoppers") in the tribe Copiphorini of the 'cone-head' subfamily. It is often confused with the closely related '' Ruspolia ni ...
'' (''Ruspolia differens'') in
Uganda }), is a landlocked country in East Africa East Africa, Eastern Africa, or East of Africa, is the eastern subregion of the African continent. In the United Nations Statistics Division scheme of geographic regions, 10-11-(16*) territor ...
and neighbouring areas.


Communication

The males of tettigoniids have sound-producing
organs In biology, an organ is a collection of tissues joined in a structural unit to serve a common function. In the hierarchy of life, an organ lies between tissue and an organ system. Tissues are formed from same type cells to act together in a f ...
located on the hind angles of their front wings. In some species, females are also capable of stridulation. Females chirp in response to the shrill of the males. The males use this sound for courtship, which occurs late in the summer. The sound is produced by rubbing two parts of their bodies together, called
stridulation Stridulation is the act of producing sound by rubbing together certain body parts. This behavior is mostly associated with insects, but other animals are known to do this as well, such as a number of species of fish, snakes and spiders. The mech ...
. In many cases this is done with the wings, but not exclusively. One body part bears a file or comb with ridges; the other has the plectrum, which runs over the ridges to produce a vibration. For tettigoniids, the fore
wings A wing is a type of fin that produces lift while moving through air or some other fluid. Accordingly, wings have streamlined cross-sections that are subject to aerodynamic forces and act as airfoils. A wing's aerodynamic efficiency is expresse ...
are used to sing. Tettigoniids produce continuous songs known as trills. The size of the insect, the spacing of the ridges, and the width of the scraper all influence what sound is made. Many species stridulate at a tempo which is governed by ambient temperature, so that the number of chirps in a defined period of time can produce a fairly accurate temperature reading. For American katydids, the formula is generally given as the number of chirps in 15 seconds plus 37 to give the temperature in degrees Fahrenheit.


Predation

Some tettigoniids have spines on different parts of their bodies that work in different ways. The Listroscelinae have limb spines on the ventral surfaces of their bodies. This works in a way to confine their prey to make a temporary cage above their mouthparts. The spines are articulated and comparatively flexible, but relatively blunt. Due to this, they are used to cage and not penetrate the prey's body. Spines on the tibiae and the femora are usually more sharp and nonarticulated. They are designed more for penetration or help in the defensive mechanism they might have. This usually works with their diurnal roosting posture to maximize defense and prevent predators from going for their head.


Defense mechanisms

When tettigoniids go to rest during the day, they enter a diurnal roosting posture to maximize their cryptic qualities. This position fools predators into thinking the katydid is either dead or just a leaf on the plant. Various tettigoniids have bright coloration and black apical spots on the inner surfaces of the
tegmina A tegmen (plural: ''tegmina'') designates the modified leathery front wing on an insect particularly in the orders Dermaptera ( earwigs), Orthoptera (grasshoppers, crickets and similar families), Mantodea (praying mantis), Phasmatodea (stick an ...
, and brightly colored hind wings. By flicking their wings open when disturbed, they use the coloration to fool predators into thinking the spots are eyes. This, in combination with their coloration mimicking leaves, allows them to blend in with their surroundings, but also makes predators unsure which side is the front and which side is the back.


Reproductive behavior

The males provide a
nuptial gift A nuptial gift is a nutritional gift given by one partner in some animals' sexual reproduction practices. Formally, a nuptial gift is a material presentation to a recipient by a donor during or in relation to sexual intercourse that is not simpl ...
for the females in the form of a
spermatophylax A spermatophylax is a gelatinous bolus which some male insects eject during copulation with females through their aedeagi together with spermatophores, and which functions as a nutritive supplement for the female. See also *Nuptial gift A nupt ...
, a body attached to the males'
spermatophore A spermatophore or sperm ampulla is a capsule or mass containing spermatozoa created by males of various animal species, especially salamanders and arthropods, and transferred in entirety to the female's ovipore during reproduction. Spermatophores ...
and consumed by the female, to distract her from eating the male's spermatophore and thereby increase his paternity.


Polygamy

The Tettigoniidae have polygamous relationships. The first male to mate is guaranteed an extremely high confidence of paternity when a second male couples at the termination of female sexual refractoriness. The nutrients that the offspring ultimately receive will increase their fitness. The second male to mate with the female at the termination of her refractory period is usually
cuckolded A cuckold is the husband of an adulterous wife; the wife of an adulterous husband is a cuckquean. In biology, a cuckold is a male who unwittingly invests parental effort in juveniles who are not genetically his offspring. A husband who is aw ...
.


Competition

The polygamous relationships of the Tettigoniidae lead to high levels of male-male competition. Male competition is caused by the decreased availability of males able to supply nutritious spermaphylanges to the females. Females produce more eggs on a high-quality diet; thus, the female looks for healthier males with a more nutritious spermatophylax. Females use the sound created by the male to judge his fitness. The louder and more fluent the trill, the higher the fitness of the male.


Stress response

Oftentimes in species which produce larger food gifts, the female seeks out the males to copulate. This, however, is a cost to females as they risk predation while searching for males. Also, a cost-benefit tradeoff exists in the size of the spermatophore which the male tettigoniids produce. When males possess a large spermatophore, they benefit by being more highly selected for by females, but they are only able to mate one to two times during their lifetimes. Inversely, male Tettigoniidae with smaller spermatophores have the benefit of being able to mate two to three times per night, but have lower chances of being selected by females. Even in times of nutritional stress, male Tettigoniidae continue to invest nutrients within their spermatophores. In some species, the cost of creating the spermatophore is low, but even in those which it is not low, it is still not beneficial to reduce the quality of the spermatophore, as it would lead to lower reproductive selection and success. This low reproductive success is attributed to some Tettigoniidae species in which the spermatophylax that the female receives as a food gift from the male during copulation increases the reproductive output of the reproduction attempt. However, in other cases, the female receives few, if any, benefits. The reproductive behavior of bush crickets has been studied in great depth. Studies found that the tuberous bush cricket ('' Platycleis affinis'') has the largest testes in proportion to body mass of any animal recorded. They account for 14% of the insect's body mass and are thought to enable a fast remating rate.


References


External links


North American Katydids
with range maps and audio files of katydid songs * {{Authority control Orthoptera families Extant Jurassic first appearances Taxa named by Hermann August Krauss