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Orthoptera of the Northern Great Plains


Anatomy of a Grasshopper

    To use keys, or to learn how to identify any object, some vocabulary (nomenclature or jargon) is necessary. Vocabulary teaches one how to observe, what to look for, or what is important. If we were discussing stamp collecting (Philately) this section would deal with commemoratives, printing errors, first day covers, and perforations, etc. If birding were the subject, we would be discussing wing-bars, culmen shape, retrices, and booted tibio-tarsi. However, our subject is ‘hoppers.

    Hoppers are members of the insect order Orthoptera. Because they are insects, hoppers have a body divided into three sections: head– with mouthparts, compound eyes and antennae, thorax– with legs and wings, and abdomen– with terminal reproductive structures. Because hoppers are Orthoptera, they have leather-like forewings called tegmina, jumping or saltitorial hind legs, and gradual metamorphosis such that after hatching, the young or nymphs pass through several growth stages or instars until they reach their final adult or imago stage. In each successive instar, the wings and reproductive structures become better developed.

    Head. Structures of the head: The head contains the large compound eyes. Above and slightly anterior to (in front of) each compound eye is a simple eye called the lateral ocellus. In face-on view is another simple eye called the median ocellus. In total then, there are three simple eyes, the two lateral ocelli and the median ocellus. Anterior to the compound eyes are the antennae. Each antenna has a movable basal segment called the scape, upon which is situated a second movable segment, the pedicel. The remaining moveable structure is the flagellum. Each subsegment of the flagellum is non-moveable and called a flagellomere.

    The lower and ventral portion of the head contains the mouthparts and associated structures. The transverse suture running across the lower part of the face is the epistomal suture. The sclerite immediately below this suture is the clypeus. Below the clypeus are the mouthparts. The moveable upper-lip or labrum is directly below the clypeus. Moving posteriad (backwards) from the labrum are, in order: mandibles, maxillae, and labium. Mandibles are the heavy chewing implements. The maxillae have segmented structures called maxillary palpi which manipulate and taste the food. The labium with labial palpi serves as the lower lip or bottom of the food chamber (also called the buccal cavity) just as the labrum is the ceiling or upper lip of the food chamber, and the mandibles and maxillary are the side walls.

    Regions of the head: The rounded most dorsal area of the head is the vertex. The somewhat flattened or impressed area anterior to the vertex and the compound eyes is the fastigum. Rectangular or triangular impressions along the anterior margin of the head and just below the fastigum are the lateral foveolae. The median ocellus is situated on a raised area called the frons or frontal costa. The frons is bordered laterally by ridges called the frontal carinae and ventrally by the epistomal suture. A vertical suture below each eye is the subocular suture. The lateral area of the head below and behind this suture or the ‘cheek’ area is called the gena.


    Thorax. Structures of the thorax: The thorax is the locomotive center of the insect as it contains the wings and legs. As a simplified model, the insect thorax can be thought of as a box. Under this analogy, the top of the box is the notum, the bottom is the sternum, and the sides are the pleura. Moving posteriad (front to back), the thorax is divided into three segments: the pro-, meso-, and meta- thorax. Areas of the thorax can then be designated such as the pronotum or the mesosternum. 

The pronotum is the most important area for of the thorax for hopper identification. A ridge running along the mid-line of the dorsal (top) surface, anteriad to posteriad (front to back) is the median carina. A ridge, more or less parallel to the median carina but running along the dorso-lateral edge of the pronotum is the lateral carina. The most posterior groove which cuts across the median carina is called the principle sulcus. The area of the pronotum anteriad of this sulcus is the prozona, while the area posteriad of this sulcus is the metazona. The most posterior portion of the metazona when viewed from above, is the posterior lobe. The posterior angle is formed by the edges of the posterior lobe. When the pronotum is viewed from the side, the rounded lobe of the pleural region is the lateral lobe

    Legs arise at the boundary between the pleural and sternal regions. The front legs are the prothoracic legs, the middle pair of legs are the mesothoracic legs, and the enlarged, jumping (saltatorial) hindlegs are the metathoracic legs. Wings arise at the boundary between the notal and pleural regions. The thickened or leathery front wings (tegmina) are from the mesothorax while the fan-like hindwings are from the metathorax.

    Insect legs possess jointed segments. Moving outward (distad) from the body these segments are: coxa, trochanter, femur, tibia, and tarsus. The front tibia of members within the suborder Ensifera have a blister-like hearing organ, the tympanum. The hind femur is the enlarged jumping spring of the hindlegs. The hind tibia has two rows of spines and as many as six enlarged movable spurs at its apex. These enlarged spurs are known as calcaria. Note that a spur is inserted into a socket and is movable while a spine lacks a socket and is fixed. The tarsus is divided into a number of segments called tarsomeres. At the end of the tarsus are two claws (tarsal claws) and a pad between these claws, not always present, is the arolium. When there are pads below the tarsal claws (other insects) these are called pulvilli. Pads present under each tarsomere are called euplantae.

    The hind femur has surfaces and structural features which are important in identification. The sharp ridge along the top of the femur is the upper carina and that along the bottom is the lower carina. The femur has an outer face and an inner face. The curving ridge on the outer face just below the upper carina is the upper carnula. The curving ridge just above the lower carina is the lower carnula. The upper and lower carnulae are separated by an area which shows a herring bone pattern of faint groves or chevrons. On the inner face of the hind femur there is usually a straight inner carnula which in the slant-faced grasshoppers, runs below a row of minute stridulatory pegs. The swollen distal end of the femur is the ‘knee’ or genu.


    Wings.  Orthoptera usually have two pairs of wings; the narrow forewings covering the fan-like hindwings. The forewings are often leathery and so are known as tegmina. When the wings are spread, the leading edge of the forewing is the costal margin and the trailing edge is the inner margin. Often the wing area immediately behind the costal margin (costal area) is enlarged and is crossed by a series of parallel veins which run obliquely (slant-wise) to the margin. This gives the area the appearance of a series of windows or fenestrae. In many grasshoppers, a raised longitudinal vein can be seen posteriad of the costal area and running parallel to the costal margin. This is the intercalary vein. Bandwing grasshoppers produce sound by rubbing the hind femur across this vein.


    Abdomen. The abdomen is essentially cylindrical with a series of dorsally over-lapping plates or tergites and a similar series of ventral plates or sternites. In the suborder Caelifera, a large blister-like structure or tympanum can be seen near the base of the abdomen. Posteriad, the abdomen has the specialized reproductive structures which are somewhat different for each suborder.

    In Caelifera, males have a triangular shield-like supra-anal plate occupying the dorsal surface posteriad. From the tergite at its base there are often two finger-like projections termed furculae. Laterally and projecting posterio-dorsad on each side is a cercus which is usually flattened but may be tapered from base to apex. Ventrally, the last segment is the subanal plate. This plate or sclerite is usually evenly rounded but may taper to a rounded or bilobed apex. The lateral edges of this plate may be straight or arched. In females, the abdomen terminates in a point which is in fact four closely appressed points. These are the ends of the paired dorsal and ventral valvulae which together make up the ovipositor. Hidden internally is an additional pair of valvulae which act as egg guides. In side view, the profile of the dorsal valvulae appears as a straight or weakly arched edge followed by the posterior scoop. The point where the dorsal edge and the posterior scoop meet is often marked by a dorsal tooth.

    In Ensifera, the male abdomen is often blunt with posterorly projecting cerci. Each cercus in the katydids and meadow grasshoppers tapers posteriad and has an inner tooth. Crickets have long tapering annulated (ringed) cerci. The ovipositors in Ensifera fall into three basic types: cylindrical, sword-like and projecting, or flattened and sharply upturned. The first occurs in the true crickets, the latter two in the katydids and allies.


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Last updated: 01/05/07    

Gerald M. Fauske
Research Specialist
202 Hultz Hall
Fargo, ND  58105
E-Mail:  Gerald.Fauske@ndsu.nodak.edu

Published by the Department of Entomology


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