Detailed External Anatomy, Grasshoppers of Wyoming and the West

Grasshoppers of Wyoming and the West

Entomology: Detailed External Anatomy

The head of the grasshopper is a hard capsule that contains large muscles, which operate the chewing mouthparts, and the brain and subesophageal ganglion, which serve as the main centers of the nervous system. Prominent on the outside of the capsule are a pair of antennae, two large compound eyes, and the downward directed mouthparts. The antennae of grasshoppers are usually filiform (threadlike) but they may have other shapes, such as ensiform (broad at base, narrowing to tip) or clavate (expanded at tip) (Fig. 2). Compound eyes vary in shape and protuberance. They are usually somewhat round but may be elliptical in grasshoppers with strongly slanted faces.

Figure 2. Diagram of three forms of grasshopper antennae: filiform or threadlike, ensiform or sword-shaped, and clavate or club shaped

Figure 3. Grasshopper head, front, side, and top views. Modeled after Trimerotropis pallidipennis (Burmeister).

The head capsule is divided into areas by visible sutures, external ridges (carinae), or by general location (Fig. 3). The top of the head between the compound eyes is known as the vertex. Behind the vertex is the occiput, and in front of the vertex is the fastigium. A pair of variously shaped depressions, the lateral foveolae, is often present in front or at the sides of the fastigium. The front of the head between the compound eyes and extending to the clypeus is known as the frons.

A wide ridge, the frontal costa, runs down the middle of the frons from the fastigium toward the margin of the clypeus. The side of the head below the compound eye is named the gena or cheek. Grasshoppers have three simple eyes called ocelli — one above the base of each antenna and one centrally located in the frontal costa. These and other parts and appendages of the head are illustrated in Figure 3.

Thorax

The thorax, locomotion center of the grass-hopper, is a stout, boxlike structure consisting of three fused segments: the prothorax, mesothorax, and metathorax. Each segment bears a pair of legs. The second segment bears a pair of fore-wings, the tegmina, and the third segment a pair of membranous hindwings. The wings of a few species are reduced to small pads or are entirely lacking. The top of the thoracic segments is called the notum, the bottom the sternum, and the sides the pleura.

Pronotum

Figure 4. Grasshopper pronotum, side and top views. Modeled after Trimerotropis pallidpennis (Burmeister).

The pronotum situated just behind the head is a prominent, saddle-shaped structure with lateral lobes that hide nearly all of the propleura (Fig. 4). The pronotum has many distinctive features useful in separating both genera and species of grasshoppers. The integument (skin) may be nearly smooth in some species and rough and wrinkled in others. The dorsum or disk of the pronotum is divided into left and right halves by a longitudinal ridge, the median carina. The ridge varies among species from barely visible to a conspicuously high crest. Transverse furrows run across the disk and down the lateral lobes. These furrows, known as sulci, cut into the median carina and divide the disk into zones, the prozona in front and the metazona in the rear. In many species only one sulcus cuts the median carina while in others two or three sulci cut the median carina. The hind sulcus is considered the principal sulcus; from its position the length of the prozona and metazona are measured.

The lateral lobes usually form an angle with the disk and are separated from the disk by lateral carinae that, depending on the species, may be straight and parallel or variously incurved or outcurved. The hind margin of the disk varies from an acute angle to an obtuse angle, or may be convex, truncate, or emarginate.

The various shapes, sizes, and protuberance of the sternal sclerites afford reliable taxonomic characters (Fig. 5). A prosternal spine located between the bases of the front legs is characteristic of members of the spurthroated subfamily. Shapes and dimensions of the mesosternal and metasternal lobes and interspaces are useful in separating certain species and subfamilies.

Sternum of Thorax

Figure 5. Sternum of thorax, bottom view. Modeled after Melanoplus bivittatus (Say) female.

Although the three pairs of legs have the same component parts, the hind pair, adapted for jumping, are much larger than the first and second pair and bear more distinctive features. The color and markings of both the femur and tibia differ among species. The robust femur has several surfaces and ridges that have been given names for easy reference (Fig. 6).

Hindleg

Figure 6. Grasshopper hindleg, views of outer and inner faces. Hindleg of Mermiria bivittata (Serville).

The long and slender tibia bears along its posterior edges a double row of spines and distally two pairs of articulated spurs or calcars. The number of spines and the length of calcars vary among species. The inner medial area of the femur may have a longitudinal ridge bearing a series of stridulatory pegs. Up and down movements of the hindlegs cause the pegs to scrape against a raised vein on each tegmen, which produces a song or signal peculiar to that species of grasshopper.

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Wings

The two pairs of grasshopper wings differ in shape, structure, and function (Fig. 7). The front pair, or tegmina, are leathery and narrow with the sides nearly parallel. The hind wings are membranous and fan-shaped. Compared with the tegmina, the hind pair contribute three times as much to flight lift. Both pairs afford diagnostic characters that aid in the identification of species. The wing veins, sclerotized tubes providing strength to the wings, vary greatly in thickness. The tegmina vary from immaculate to distinctly spotted or marked. The hindwings of grasshoppers are usually hyaline. Members of one subfamily, the Oedipodinae or bandwinged grasshoppers, have wings with a dark submarginal band and have the disk colored.

Figure 7. Bandwinged grasshopper with left wings spread, top view. Composite model

Abdomen

The hind region of the grasshopper’s body, the abdomen, consists of 11 segments (Fig. 1). Segment I is firmly fused with the metathorax and contains the auditory organ with its eardrum cover, the tympanum (Fig. 8).

Figure 8. Grasshopper male abdomen, side view and enlarged side and dorsal views of end. Modeled after Melanoplus packardii Scudder.

Segments II to VIII are ringlike in appearance and are separated from one another by pliable membranes. Each segment has a sclerotized tergum that covers not only the top but also the sides of the abdomen. A sclerotized sternum covers the bottom. Pliable membranes separate the terga from the sterna and with the intersegmental membranes allow the abdomen much flexibility, a requirement for respiratory movements, copulation, and oviposition.

Genitalia

The terminal segments of the abdomen are reduced and modified to bear the external reproductive organs, the genitalia, and the associated structures (Fig. 8). These structures offer the most reliable taxonomic characters for separating spurthroated grasshoppers. Structures of the male are more distinctive than those of the female. The prominent paired cerci are usually conical, but in the males of some genera, e.g. Melanoplus, they have characteristic sizes and shapes.

Likewise, the furcula, a pair of projections from the posterior edge of tergum X of males, differs in size and shape. The epiproct or supraanal plate, although roughly triangular, varies sufficiently in shape and rugosity to be taxonomically useful.

The variations in shape and protuberances of the subgenital plate are also useful in identification. These structures are easily seen with a pocket magnifier of 10x magnification. A few distinctive structures, such as the lobes of the aedeagus, require the use of a stereomicroscope (magnification of 50x and greater) for clear identification.

The valves of the ovipositor are sometimes useful in separating species (Fig 1). The dorsal and ventral pair of valves have various shapes and denticulations. The middle pair of valves are small and hidden.

The sclerotized integument of the abdomen varies in color, patterns, and texture among species and sometimes affords distinguishing taxonomic characters.

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Grasshopper Anatomy

Grasshopper Anatomy Like all insects, the grasshoppers have three main body parts – the head, the thorax and the abdomen. They have six jointed legs, two pairs of wings and two antennae. Their body is covered with a hard exoskeleton. Grasshoppers breathe through a series of holes called ‘spiracles’ which are located along the sides of the body. Most grasshoppers are green, brown, or olive-green.

The biggest Grasshoppers are about 4.5 inches (11.5 centimetres) long. Their legs are long hind legs that are used for hopping and jumping. The short front legs are used to hold prey and to walk.

Abdomen – the segmented tail area of a grasshopper, which contains the heart, reproductive organs, and most of the digestive system.

Antennae – like all insects, grasshoppers have 2 segmented antennae that sense touch and odours.

Compound eye – grasshoppers have 2 faceted eyes made up of many hexagonal lenses.

Head – the head is at the front end of the grasshoppers body and is the location of the brain, the two compound eyes, the mouth parts, and the points of attachment of its two antennae.

Jumping legs -the long, hindmost pair of the grasshoppers six legs.

Mandibles – the jaws, located near the tip of the head, by the palps; the jaws crush the food.

Palps – long, segmented mouth parts (under the jaws) that grasp the food.

Spiracles – a series of holes located along both sides of the abdomen; they are used for breathing.

Thorax – the middle area of the grasshoppers body – where the legs and wings are attached.

Walking legs – the four, short front legs that are used for walking and holding prey while they eat.

Wings – grasshoppers have two long wings which they use for flying.

Short-horned grasshoppers have ears in the sides of the abdomen.

Long-horned grasshoppers and crickets have ears in the knee-joints of their front legs.

How Do Grasshoppers Jump?

A good ‘jump’ means that the legs must push against the ground with high force and high speed.

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The ultimate source of this push comes from the contraction of the muscles inside the leg, this give the jump the catapulting effect.

To get a good jump requires two things.

1. The legs have to thrust on the ground with a lot of force. If the thrust is too low, the animal does not get a fast enough take-off and it does not jump very far.

2. The legs have to develop this force quickly.

If the thrust builds up too slowly, the legs will extend before the thrust reaches its maximum.

Once the grasshopper is standing on tip-toe, it cannot thrust against the ground any more, therefore, it is ‘take off’ time and off it goes.

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Grasshopper Location

The grasshopper is a medium to large sized insect and the grasshopper is found (close to grass) all over the world. Grasshoppers are best known for their ability to jump incredible heights and distances.

Most grasshopper individuals grow to about 2 inches long although larger grasshoppers are found on a fairly regular basis that grow to more than 5 inches in length. The grasshopper has wings meaning it can migrate over long distances when the weather gets too cold.

There are 11,000 thousand known species of grasshopper on Earth, that live in grassy areas such as fields and meadows and forest and woodland. Like all insects, all species of grasshopper have a three-part body that is made up of the grasshopper’s head, it’s thorax and the abdomen. Grasshoppers also have six legs, two pairs of wings, and two antennae.

The antennae of the grasshopper are known to be remarkably long and can often be longer than the grasshopper’s body, although the grasshopper’s antennae and the grasshopper’s body are normally about the same size. Grasshoppers use their long antennae in order to make sense of their surroundings.

Grasshoppers have six jointed legs that are incredibly powerful for such a small creature, as grasshoppers are able to jump extraordinary distances. The two back legs of the grasshopper are long and powerful and are just for jumping, where the four front legs of the grasshopper are primarily used to hold onto prey and to help it to walk.

Despite their large size, grasshoppers are herbivores animals and have a diet that consists solely of plant matter. Grasshoppers eat grasses, weeds, leaves, shrubs, bark and numerous other species of plants that surround them.

The grasshopper is also a stable food source for many predators around the world including reptiles, insects, small mammals and birds. It is common for humans to eat grasshoppers in places like Asia and Africa where the bigger species of grasshopper are found, and there is a less readily available alternative protein source.

The female grasshopper lays an egg pod that contains a couple of dozen grasshopper eggs in the late autumn to early winter depending on the area. The female grasshopper inserts her egg pod into the soil so that it is a couple of inches underground. The grasshopper eggs can take up to 9 months to hatch as they wait until the weather has warmed before breaking into the outside world.

When the first baby grasshopper (known as a nymph) hatches out of its egg, it tunnels through the soil and up to the surface, and the remaining grasshopper nymph follow.

As they get older, the grasshoppers will increase in size until they are adults. The grasshopper only remains in this stage (young and adult) for a few months before it dies meaning that most grasshopper individuals spend the majority of their lives inside an egg.

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How to Identify Locusts & Grasshoppers

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The sound of grasshoppers brings to mind warm, lazy summer days spent lying in long grass for most of us; but among farmers, grasshoppers and locusts have a more sinister reputation as crop-destroyers. Most short-horned grasshoppers and all locusts belong the same family, Acrididae, and are very similar insects. Locusts differ mostly in their ability to change appearance and behavior in response to population increases and reduction in food supplies. Long-horned grasshoppers, or katydids, also look similar, but are members of the Tettigoniidae family.

Grasshoppers share many features with other insects, including six legs, a separate head, abdomen and thorax, and a hard, chitinous shell.

Different species range in size between 1/2 inch and 2 3/4 inches, or 7 centimeters. Grasshoppers have long hind legs, large eyes, a single pair of antennae, and two pairs of wings. Their front wings are thin and tough, and their back wings are wide and flexible. In some species the wings are brightly colored, but most grasshoppers’ coloring is green, brown or gray, to help them blend into their environment. Grasshoppers also have large mouthparts for chewing. Long-horned grasshoppers’ identifying characteristic is their antennae, which are longer than their wings, while short-horned grasshoppers have short, stubby antennae.

Locusts

Locust bodies undergo changes when they turn from solitary to swarming behavior. Their wings grow larger, enabling them to fly great distances; some species change color or appearance. Migratory locusts’ (Locusta migratoria) heads become more streamlined, and desert locusts (Schistocerca gregaria) change from green to black with orange spots. Locusts have two phases, solitary and swarming. Female locusts are larger than males when species are in the solitary phase; but when they’re swarming, size differences reduce and sometimes disappear entirely. Most grasshoppers look similar as they grow, increasing in size in five or six stages, gaining wings in their final, adult stage.

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Social Behavior

Grasshoppers and locusts have different patterns of social behavior that can help identify them. A single insect could be a grasshopper or a locust, but a band of insects in close proximity to one another are almost certainly locusts. Grasshoppers tend to be solitary insects, only meeting others to mate and reproduce. Locusts are solitary only sometimes. They change from solitary to gregarious or swarming when their populations achieve a certain density, and often if surrounding vegetation becomes dry. Instead of avoiding each other, they seek out other locusts and complete they daily activities of feeding, basking, moving and roosting in groups or bands.

Migration

Grasshoppers and locusts are similar in their preferences for specific habitats, but locusts range widely, migrating to different areas. Most grasshoppers remain roughly where they hatched, living in open, dry grassland and scrub, and also often invading adjacent farmers’ fields. When swarming, locusts travel large distances in bands and also fly long distances when solitary. The Food and Agriculture Organization of the United Nations’ guidelines on desert locusts states crawling locusts have been recorded traveling 650 feet to 5,500 feet. Solitary locusts may fly 870 miles in one day.

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Parts of a Grasshopper

Jiminy Cricket! If you thought the puppet’s friend in the fairy tale “Pinocchio” was really a grasshopper, you were mistaken. It really was a cricket, and the two are different insects. This article will take a look at the grasshopper.

The grasshopper belongs to the order Orthoptera, in the suborder Caelifera. This amazing insect only eats plants but it has long, strong, back legs which enable it to leap twenty times the length of its own body.

The grasshopper’s total lifespan is about one year, but it lives only one month in the adult stage. There are thousands of grasshopper species. These insects range in size from about 1 inch to 4.5 inches, and in color from brown, to grey to green. Their coloration is suited to blend into the background of their habitat.

The body structure of the adult grasshopper is suited to its lifestyle. Like all insects, its body is divided into three parts: head, thorax and abdomen.

The head is the first body region. On each side of its head, the grasshopper has a large compound eye, that is, each eye is made up of many smaller eyes, giving it a wide field of vision. It also has three simple eyes, which just look like dots. It has two segmented antennae, with which it can smell and feel. Grasshoppers have no ears. They hear with an organ called tympanum at the base of their abdomen. They have no teeth, but use two bony organs called mandibles to bite off and grind the plants they eat.

Immediately behind the grasshopper’s head is the second body region, the thorax, which has three segments. Attached to each segment is a pair of legs. The four front legs are short, slender and used for walking and holding prey. Near the base of each middle leg is a small hole called the thoracic spiracle which is used for breathing. The hind legs are large, muscular, jointed, and used for jumping.

Most grasshoppers have two pair of wings attached to the second and third segments of the thorax. The fore wings are longer and leathery. They protect the hind wings which are soft and membranous, and fold up like fans when the insect is not flying. They use their wings to make short flights, which allows them to look for food over a greater area.

The third body region is the abdomen, which contains eleven segments. The tympanum, the membrane which functions as an ear, is located on the underside of the first segment. Along each side of the abdomen are tiny pinprick-like holes called spiracles, through which the grasshopper breathes in oxygen and exhales carbon dioxide.

The final section of the abdomen is smaller and contains the grasshopper’s reproductive organs. The female has a short, strong structure called an ovipositor through which she can dig and lay her eggs. The final section of the male’s abdomen is rounded.

Well, are you still wondering about the difference between grasshoppers and crickets? If you observe the habits of each insect closely, here’s how you can tell. Grasshoppers are active during the day, while crickets prefer to come out at dusk and stay up all night. In addition, grasshoppers are strictly plant eaters while crickets like a little bit of animal material in their diet. Now you know, and it’s quite possible that even Pinocchio was not able to tell the difference.

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