File: <orthoptera

The order Orthoptera -- <Adults > & <Juveniles > --, meaning "straight-winged, are large insects and among the most injurious of all insects. They have biting mouthparts, and their hind legs have enlarged femora for jumping. The fore wings are straight and leathery and are modified as tegmina, which overlap each other, while the hind wings are fanlike. The cerci are unjointed and the pronotum has enlarged lobes that hide the pleural wall. The ovipositor is well developed, and there are specialized stridulatory organs.

This order includes grasshoppers, locusts and crickets. Among the grasshoppers are the katydid or long-horned grasshopper Tettigoniidae= <Habits >; <Adults > & <Juveniles> -- with large sword-like ovipositors consisting of three pairs of valves borne on the 8th and 9th abdominal segments. By means of these the eggs, not enclosed in an ootheca, can be deposited in plant tissues, on which these insects regularly feed. The antennae also are long, often extending backwards beyond the apex of the abdomen. Stridulation is brought about by rubbing a toothed ridge on the left tegmen against an analogous region of its right counterpart. This latter has a smooth tense membrane and acts as a resonator when the tegmina are in motion and the noise, produced mostly at night, can be very loud. Auditory organs of some complexity are situated in each fore tibia. The Mormon cricket, Anabrus simplex Haldeman, can be a serious pest of agricultural crops in the Intermountain area of western North America. A miracle of sorts occurred in Utah where a serious outbreak of these crickets was destroying agricultural crops, but which was significantly reduced by seagulls (Larus californicus) (Borror, D. J. et al. 1981).

Other grasshoppers and locusts differ from these in their shorter antennae, which are hardly ever as long as the body, and in their less prominent ovipositor, the valves of which are short and curved. Rubbing the inner edges of the hind femora that bear pegs against the hardened veins on the tegmina produces stridulation in these short homed grasshoppers and locusts. The tegmina then vibrate to make a low buzzing sound.

The long established family name Gryllidae -- <Habits>; <Adults > & <Juveniles> -- has been used for the true crickets, but current changes in classification does not distinguish them as a clear taxonomic group (see Orthoptera Classification). They more closely resemble the long-homed grasshoppers in their antennae, ovipositor and stridulatory apparatus, and appear to be directly related to them. Gryllus domesticus, the house-cricket, competes with the cockroaches for a place in domestic dwellings and leads there a similar life. Gryllotaipa gryllotaipa, the mole cricket, is subterranean in habit. It is possible to estimate ambient temperature from the rate of their crick crick chirps. [Also see: Gryllacrididae <Habits>; <Adults > & <Juveniles> --].

Migration of Orthoptera

Members of the Acrididae are noteworthy for their gregarious and migratory instincts. A species, such as Locusta migratoria, generally leading a relatively harmless existence as a solitary grasshopper, may under certain conditions develop in inestimable numbers which, after traveling long distances, invade cultivated districts causing enormous harm. Thus in the case of Locusta migratoria, when environmental conditions favor an increase in numbers, there is an usual trend towards the production of swarming migrants, i.e. the gregarious phase. The subsequent decline in numbers leads to the production of solitary nonmigrants, i.e. the solitary phase. The two phases differ morphologically, biologically and in distribution so markedly as to have been regarded as distinct species. Between them are short-lived individuals that form a series with no set characters, merging barely the gregarious phase at one end and into the solitary phase at the other. The Rocky Mountain grasshopper of North America, Melanoplus mexicanus, once had a migratory phase, which has since disappeared.

NEW ORDER: Blattaria

(Previously = Superfamily Blattoidea)

These are the cockroaches, sometimes called "water bugs", that have generalized biting mouthparts and a five-jointed tarsus. They are considered as probably the oldest group of present day insects. The anterior wings are narrower and stouter than the posterior ones, which are more membranous and fold like a fan. Jointed cerci & styles occur in adult males only. The ovipositor is small or absent. The metamorphosis is hemimetabolous. Eggs are laid in beanlike capsules or oothecae that are produced by secretions of female accessory glands. The female may deposit these all at one time, or they may be carried around until they hatch.

Blatella germanica

All cockroaches are insects of substantial size. They have dorsoventrally flattened bodies, a pronotum, which is large, wide, or shield-like, and powerfully developed legs for rapid running. The coxae are broad so as to protect the lower surface of the body.

They are in commonly tropical or subtropical insects although they have adapted to living in dwellings in temperate zones. Their mouthparts indicate their omnivorous habit, as also is their alimentary canal. Strongly cuticularized toothed mandibles are followed by prominent maxillae, each of which bears a five-jointed palp, a toothed setose lacinia and a sensory flexible galea. The labium has a four-lobed ligula consisting of a pair of small glossae flanked by larger paraglossae. The labial palps are three-jointed.

The alimentary canal has a pair of salivary glands developed on the labial segment, which secrete amylase. A huge thin-walled crop leads into a gizzard-like proventriculus, the inner lining of which is provided with prominent cuticular jaws and spiny pads. These, worked by circular and longitudinal muscles, break up the food into fine particles and to filter it in its passage to the mid gut.

The mid gut is the site of the formation of a full complement of enzymes suitable to the mixed diet on which the animals feed. Examples are the cockroaches Periplaneta americana and P. australasiae and the less common German form, Blattella germanica.

Cockroaches are nocturnal in their habits and omnivorous. They are also gregarious.

Superfamily: Mantoidea

The Mantids -- <Adults> & <Juveniles> -- are predacious subtropical and tropical insects and may be considered as the only beneficial Orthoptera as they feed on any insect that comes within their grasp. Their main character lies in the fore limbs that are raptorial and the femur bears a ventral longitudinal groove surmounted at its two edges by strong spines. Into this groove fits the blade-like tibia, its sharp-toothed edge impaling the prey against the femur. The prothorax is long, and in conformity with the slenderness of the two posterior pairs of legs the insect moves only slowly and in a lumbering fashion. Otherwise their characteristics are similar to the Blattoidea as noted above. Mantis religiosa of southwestern Europe is an example (Borradaile & Potts, 1958).

Suborder: Phasmatodea

The Phasmatodea are the stick insects, which resemble twigs or leaves of plants. They are vegetarian and their body is very slender and long. They do not have their hind femora enlarged and they do not jump. The tarsi are commonly 5-segmented. The body is elongated and sticklike and the wings are either reduced or entirely absent. Their eggs are laid singly and there is no ootheca. Some tropical species are called "leaf insects" because they are flattened and expanded laterally and usually have their hind wings well developed. They do not possess tympana and stridulatory organs, the cerci are short and have only one segment, and the ovipositor is short and hidden.

The walking sticks of North America are slow moving herbivorous insects that occur on trees and shrubbery. They can emit a strong odor from glands on their thorax, which is a means of defense. They are also able to regenerate lost legs to a great extent. At times their populations can become epizootic on trees, which causes considerable damage.

There is usually only a single generation per year with an overwintering egg stage. Eggs may remain dormant into a second year and frequently populations are only abundant on alternate years.

Orthoptera Damage & Control

During the 20th Century the Chlorinated Hydrocarbons were widely used to control grasshoppers in North America and Africa, where great damage was inflicted on agricultural crops. The Desert Locust, Schistocerca gregaria, of Africa has been considered the most destructive insect in the world. It is responsible for periodic famine. It migrates from central Africa to more northern regions where the damage caused is severe. With the ban of these insecticides in North America cultural means of control were substituted, which requires plowing the fields before springtime.

Cockroaches may be controlled with poisoned baits, but sanitation is the most effective way to reduce their invasion into home areas. However, neighboring dwellings that harbor large populations of roaches may pose a threat because they are able to travel through the sewer systems.

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Orthoptera --Biological Control Projects (1% of total projects)

Cockroaches, Blatella, Blatta, Periplaneta, & Supella <ch-27.htm>

Details of Insect Taxonomic Groups

Examples of beneficial species occur in almost every insect order, and considerable information on morphology and habits has been assembled. Therefore, the principal groups of insect parasitoids and predators provide details that refer to the entire class Insecta. These details are available at <taxnames.htm>.

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Introduction Contents►

References

Borror, D. J., D. M. DeLong & C. A. Triplehorn. 1981. An Introduction To The Study of Insects, 5th ed. Saunders Publ.,

NY. 827 p.

Introduction Contents►