直翅亚目亚目

外形

蝗虫腿部发达，用后腿可以跳比身体长数十倍的距离，后翅呈半透明，体色有绿色和褐色（与品种无关；是生活环境的保护色）。

蝗虫属不完全变态昆虫，稚虫和成虫相似，只有翅膀有无的分别。

食性

蝗虫口大、下颚发达，主要以植物叶片为食，常在田间、草丛间出没。相较之下，型体与蝗虫相似的螽斯则是杂食性的物种。

求偶

一些种类的雄虫会以磨擦翅膀和后腿发出声音，吸引雌虫，与蟋蟀用前翅的发音器官发声的方式不同。

变异

有些种类的蝗虫，在繁衍过剩，以致种群密度极高，食物短缺的情况下，便会改变体色、行为和生活型态，成群结队迁移至新的地方寻找食物。某些种类的蝗虫翅膀退化变小，也有一些种类甚至已丧失飞行能力，如“菱蝗”。

The Caelifera are a suborder of orthopteran insects. They include the grasshoppers and grasshopper-like insects, as well as other superfamilies classified with them: the ground-hoppers (Tetrigoidea) and pygmy mole crickets (Tridactyloidea). The latter should not be confused with the mole crickets (Gryllotalpidae), which belong to the other Orthopteran suborder Ensifera.

The name of this suborder comes from Latin meaning chisel-bearing ("chisel" in Latin: caelum), referring to the "stout" shape of its species' ovipositors.

Subdivisions and their distribution

The Caelifera include some 2,400 valid genera and about 12,000 known species. Many undescribed species probably exist, especially in tropical forests. The Caelifera have a predominantly tropical distribution (as with most Orthoptera) with fewer species known from temperate climate zones. Caelifera are divided into two infraorders: the Tridactylidea and the Acrididea, or grasshopper-like species. This latter name is derived from older sources, such as Imms, which placed the "short-horned grasshoppers" and locusts at the family level (Acrididae).

• Infraorder Tridactylidea
• Tridactyloidea Brullé, 1835: pygmy mole crickets - all continents except Antarctica
• Dzhajloutshelloidea Gorochov, 1994 †
• Infraorder Acrididea

Tetrigoidea (monotypic) Serville, 1838: groundhoppers or "grouse locusts" - all continents except Antarctica

Informal superfamily group Acridomorpha - the grasshoppers

Acridoidea MacLeay, 1821: most grasshoppers – World-wide - approx. 10,000 species in the Acrididae alone

• Eumastacoidea Burr, 1899: "monkey grasshoppers" - Americas, Africa, Australasia
• †Locustopsoidea Handlirsch, 1906
• †Locustopsidae
• †Locustavidae
• Pneumoroidea Blanchard, 1845: "bladder grasshoppers" - Africa
• Proscopioidea Serville, 1838 - south America

Pyrgomorphoidea (monotypic) B. von Wattenwyl, 1882: "gaudy grasshoppers" - all tropical/subtropical continents

Tanaoceroidea (monotypic) Rehn, 1948: "desert long-horned grasshoppers" - north America

Trigonopterygoidea Walker, 1870: "razor-backed bush-hoppers" - Central America, south-east Asia

Affiliations

The phylogeny of the Caelifera, is described in detail for grasshoppers, with six out of eight extant superfamilies shown here as a cladogram. Like the Ensifera, Caelifera and all of its superfamilies appear to be monophyletic.

The phylogeny of the Caelifera, based on mitochondrial ribosomal RNA of thirty-two taxa in six out of seven superfamilies, is shown as a cladogram. The Ensifera, Caelifera and all the superfamilies of grasshoppers except Pamphagoidea appear to be monophyletic.

In evolutionary terms, the split between the Caelifera and the Ensifera is no more recent than the Permo-Triassic boundary; the earliest insects that are certainly Caeliferans are Eolocustopsis of family Eolocustopsidae from the latest Permian (Changhsingian) of the Beaufort Group, South Africa, followed by Locustavidae and Dzhajloutshellidae from the mid-Triassic (Ladinian age), roughly 242 to 237 million years ago. The group diversified during the Triassic and have remained important plant-eaters from that time to now. The first modern families such as the Eumastacidae, Tetrigidae and Tridactylidae appeared in the Cretaceous, though some insects that might belong to the last two of these groups are found in the early Jurassic. Morphological classification is difficult because many taxa have converged towards a common habitat type; recent taxonomists have concentrated on the internal genitalia, especially those of the male. This information is not available from fossil specimens, and the paleontological taxonomy is founded principally on the venation of the hindwings.

The Caelifera includes some 2,400 valid genera and about 11,000 known species. Many undescribed species probably exist, especially in tropical wet forests. The Caelifera have a predominantly tropical distribution with fewer species known from temperate zones, but most of the superfamilies have representatives worldwide.

Economic significance and terminology

A number of species, especially in the Acridoidea, are significant agricultural pests, but not all of them are locusts: a non-taxonomic term referring to species whose populations which may change morphologically when crowded and show swarming behaviour. Examples of agricultural grasshopper pests that are not called locusts include the Senegalese grasshopper and certain species in the Pyrgomorphidae, notably the variegated grasshopper (Zonocerus variegatus).