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Intro 1

This document provides an introduction to grasshoppers found in Florida. It describes the purpose of identifying grasshoppers and provides descriptions of grasshopper morphology and anatomy to allow for identification. Key structures for identification, such as the antennae, legs, wings and ridges on the thorax are described. The document also notes there are approximately 70 grasshopper species in Florida.

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0% found this document useful (0 votes)
58 views6 pages

Intro 1

This document provides an introduction to grasshoppers found in Florida. It describes the purpose of identifying grasshoppers and provides descriptions of grasshopper morphology and anatomy to allow for identification. Key structures for identification, such as the antennae, legs, wings and ridges on the thorax are described. The document also notes there are approximately 70 grasshopper species in Florida.

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lizawillam2023
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© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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I ntroduction

The purpose of this guide to the grasshoppers (family Acrididae) found in Florida is to describe
and portray the species in a manner that allows ready identification by the reader. It is designed
for anyone interested in natural history, not just scientists and future scientists. In striving to
make it “user friendly” we have attempted to minimize scientific terminology. Where it was
necessary to use scientific terminology, we provide definitions and drawings to increase com-
prehension and ease of use. Where possible, we have used both the common, or English,
name and the scientific name, for both grasshopper species and subfamilies. Most of the com-
mon names originate with Blatchley (1920) or Helfer (1972). There is nearly universal agree-
ment on the scientific names, but not the common names. Therefore, it is really better to use
the seemingly unpronounceable scientific names, because at least there is some consistency.
The body length measurements provided in the text are total maximum body length, includ-
ing wings but excluding antennae and legs. Therefore, for long-winged species the measure-
ments are taken from the front of the head to the tip of the folded wings. For short-winged
species, of course, the measurements are taken from the front of the head to the tip of the
abdomen. All measurements are given in millimeters (mm); if you would like to use inches, just
remember that there are 25 mm to the inch.
Grasshoppers are among the largest and most plentiful of insects, yet they are poorly known.
With this guide you can identify all the grasshopper species that inhabit Florida, and many
species also found in nearby states. It appears that there are 70 species in Florida. You also can
learn about their natural history, their distribution within the state, and how to collect and
preserve them. It is hard to imagine another group of insects so accessible and identifiable, yet
providing so exciting a challenge for collectors. To collect examples of all of Florida’s grasshop-
pers, one must be willing to traverse the state from the Panhandle to the Lake Okeechobee
area and endure the rigors of Florida’s hot, humid, sandy, marshy and densely forested habi-
tats. Because many of Florida’s grasshoppers are poorly known, you can make a real contribu-
tion to the scientific study of insects by recording where these species are found, what they feed
upon, and the time of the year they are abundant.
A central repository for insects and insect biology is the collection of the state insect mu-
seum, which consists of over 7 million insects:

Florida State Collection of Arthropods


Florida Department of Agriculture and Consumer Services
Division of Plant Industry
1911 SW 34th Street
Gainesville, Florida 32608

1
What is a Grasshopper?
There are several closely related groups of insects in the order Orthoptera that are sometimes
called grasshoppers. However, most entomologists and non-entomologists consider only in-
sects in the family Acrididae to mean “grasshopper.” Indeed, we consider only members of this
family in our treatment of Florida grasshoppers. Acrididae are sometimes referred to as the
short-horned grasshoppers, a reference to their relatively short antennae. However, other fami-
lies that are sometimes thought of as grasshoppers include the Tetrigidae, or pygmy grasshop-
pers; the Eumastacidae, or monkey grasshoppers; the Tanaoceridae, or desert long-horned
grasshoppers; the Tettigoniidae, or long-horned grasshoppers or katydids; the Gryllacrididae,
or wingless long-horned grasshoppers; and perhaps other small families. Other than the acridids,
only the tettigoniids are known to most people, and they are usually known as katydids or
coneheads. Of the grasshoppers and their close relatives, only Acrididae and Tettigoniidae are
common in Florida.
Acridid grasshoppers usually are large insects. Their antennae are relatively short, usually
less than half the length of their body. Acridids may be winged or wingless, but if winged they
have four wings. Wing size varies considerably. Short-winged forms are flightless, whereas
long-winged forms are sometimes strong fliers. The forewings, or first pair of wings, are some-
what thickened and pigmented. They are called tegmina. The hind wings are not thickened,
and may range from unpigmented to brightly colored. The hind wings often are large, fan-
shaped, and fold up under the forewings when the insect is not in flight. Grasshoppers tend to
have long legs. The hind legs are especially elongate and enlarged to facilitate leaping, as well
as armed with spines for defense.
Grasshoppers produce sound by rubbing one part of the body against another, though the
parts involved may vary. Their hearing is often aided by the presence of tympana, auditory
organs on the sides of the first abdominal segment. Singing is performed principally by males
as part of their courtship ritual.

hind femur
pronotum tibia
forewing

spur
lateral tarsus
spine
lobe of
pronotum

head thorax abdomen

The Parts of a Grasshopper


The morphology, or appearance, of grasshoppers can seem complex, especially because of the
foreign-sounding names affixed to many structures. However, one need examine only the color
and shape of a few structures to accurately identify grasshoppers. It is not much more difficult
than identifying birds, and often does not require great magnification. Grasshoppers can be
identified with no more than a 10× hand lens, which is readily available from any hobby shop.
We have attempted to simplify the identification of grasshoppers by minimizing the use of
terminology and by providing a glossary and drawings of the body parts.

2
The grasshopper body is divided into 3 basic components: the head, which bears the sen-
sory structures such as eyes, antennae, and mouthparts; the thorax, which bears the structures
associated with movement, namely the legs and wings; and the abdomen, which bears the
digestive and reproductive structures. A few elements associated with each of these body seg-
ments provide the key structures for grasshopper identification.
On the grasshopper head, the principal structures used for identification are the antennae,
sensory structures attached to the front of the head between the eyes. Most grasshopper anten-
nae consist of a string of small, barrel-like segments, although the individual segments are
sometimes quite elongate. Some species, however, have flattened antennal segments, and
many have flattened segments that are larger toward the base of the antenna and smaller
toward the tip. Such antennae are said to be sword-shaped. A feature that is important in a few
species is the shape of the vertical, flattened, elevated structure on the front of the head, called
the frontal ridge.

antenna

median ridge
leading edge
sulcus
forewing
lateral ridge

wing tip
band

femur

hind wing
abdomen
cercus tibia

supra-anal plate
tarsus

The thorax consists of three segments, although this is not readily apparent because the first
of the three segments, the prothorax, is enlarged and covers the other segments when viewed
from above. The prothorax often bears longitudinal ridges, sometime called carinae. The shape
of the medial or central ridge, or the paired lateral ridges, is sometimes diagnostic. The ridges
may be cut by crevices, called sulci. One pair of legs is attached to each of the thoracic seg-
ments, with the third pair, or hind legs, enlarged. The important hind leg segments, from the
perspective of identification, are the large, thickened femur (plural, femora) and the long, thin
tibia (plural, tibiae). Attached to the second and third thoracic segments are the wings (if they
are present). The forewings, also called tegmina, attach to the middle, or second, thoracic
segment, and tend to be narrow, thickened and pigmented. The forewings overlay the hind
wings, which are attached to the posterior, or third, thoracic segment. The hind wings usually
are broad, thin, and transparent. The hind wings provide most of the lift used for flight, and
remain folded and unseen until the insect flies. Wing length varies within some species, but is
commonly used to distinguish among species. Species that inhabit open environments where
flight is easy, such as pastures and marshes, usually are long-winged (macropterous). In con-
trast, species that inhabit dense vegetation and undergrowth, where flight is perhaps more
difficult, are more likely to be short-winged (brachypterous).

3
The abdomen is the largest and hindmost compo- supra-anal plate cercus
nent of the grasshopper body. It bears the reproduc-
tive structures terminally. In some groups, small paired
appendages called cerci are species-specific in shape
among males. Another structure that aids identifica-
tion is the furcula, a forked organ in which only the
two tips of the fork are visible, making it appear that
subgenital
there are two structures rather than one. In males, the plate
furcula rests on a broad, flat, dorsal plate near the tip Male
of the abdomen called a supra-anal plate. The tip
of the abdomen in males is called the subgenital
furcula
plate. It is mostly a ventral and apical structure, topped
supra-anal
dorsally by the supra-anal plate. The shapes of both
plate
the supra-anal plate and subgenital plate sometimes
cercus
have diagnostic value. Beneath the supra-anal plate
of males is the aedeagus, or penis. We do not de- subgenital
plate
scribe this structure because it is internal, and exami-
nation requires difficult manipulation of the specimen
and significant magnification. However, the form of Male
the aedeagus may be critical in sexual compatibility,
and its shape is an excellent indicator of identity in
some grasshoppers.
In females, the tip of the abdomen is dominated by
the ovipositor. It consists of curved, pointed struc- ovipositor
tures that open upwards and downwards. The ovi-
positor is inserted into the soil and used to dig a hole
to prepare for egg laying. The ovipositor has great di-
agnostic value in distinguishing the sex, but very lim- Female
ited value in species identification.
Tip of abdomen in adult male and female
grasshoppers.

The Life History of Grasshoppers


The life history of grasshoppers is relatively simple, although it varies somewhat among differ-
ent species. The principal stages are the egg, nymph, and adult. Grasshoppers undergo gradual
metamorphosis (i.e., the nymph gradually changes to the adult form), in contrast to the
higher insects, which undergo complete metamorphosis (i.e., there is a pupal stage between
the immature and adult stages).
Adult females produce eggs, which are deposited in clusters, usually in the soil. Clusters of
eggs are usually held together by a frothy secretion that, when dry, forms a rigid covering over
the eggs. The eggs and frothy secretion are collectively known as an egg pod. A pod may
contain 4 to over 100 eggs, depending on the grasshopper species. Grasshoppers typically pass
winter in the egg stage. In Florida, however, many species survive the winter months in the
nymphal and adult forms. This is especially true in the southern half of the state.
When a grasshopper egg hatches, the young grasshopper digs its way through the soil to the
surface and molts into an active form capable of walking, hopping, and eating. The active
stage between hatching and adulthood is called a nymph. This first active form is known as the
first instar. It is followed by additional molts until it has experienced (usually) 5 or 6 instars, and
is ready for its final molt to the adult form. The principal reason that insects molt, or shed their
old body covering, is because the covering is not elastic and inhibits growth. Thus, each time
the grasshopper nymph molts it produces a larger body covering, and the nymph gets larger
and larger. As grasshopper nymphs grow the wings begin to develop, but they are not fully
formed until the adult stage. Sexual structures, such as the ovipositor in females, also develop
as the grasshoppers grow. These, too, are not fully formed until the adult stage.

4
The nymphal instars can be distinguished by the shape
of the wing pads. The wing pads initially are very short
and broadly rounded, but become slightly elongated in
instar 2. Instars 3 and 4 have more elongate, downward
Instar 1 Instar 2 pointing wing pad tips, and display some weak wing veins.
In instars 5 and 6 the wing pads are inverted; they point
upward or back instead of downward, and only one pair
of wings is visible. In grasshoppers with only five instars,
the pattern is much the same, but the fourth nymphal stage
Instar 3 Instar 4 is absent from the developmental sequence.
Adult grasshoppers can reproduce, and have fully
formed sexual organs, some of which are visible exter-
nally. They also have fully formed wings. Many species
are macropterous, or long-winged, which means that the
Instar 5 Instar 6
wings extend nearly to the tip of the abdomen or beyond.
Anterior region of grasshopper Many of Florida’s grasshoppers, however, are brachypter-
nymphs showing wing characters ous, or short-winged, in the adult stage. Such wings are
that are used to distinguish instars in typically oval and extend only about one-third the length
“typical” species. of the abdomen. A few species are wingless, or nearly so,
in the adult stage. It can be difficult to distinguish between
immatures and adults when adults can be long-winged, short-winged, and wingless! However,
if you look for obvious, fully formed genitalia, and wings extending at least one-third the length
of the abdomen, you will identify most adults accurately. Only in a few species are adults likely
to look like immatures, and they are easily recognized from pictures.
In the “typical” grasshopper life cycle, eggs hatch in the spring, nymphs develop through
the summer, adults mate and produce eggs in the late summer and autumn, and the winter is
passed in the egg stage. How many grasshoppers conform to this scenario? In northern Florida,
most species seem to conform. In southern Florida it is not uncommon to have nymphs and
adults present nearly year round. Unfortunately, grasshoppers have been poorly studied in
Florida, so in most cases we do not know much about seasonal development. In the case of
Schistocerca americana we know that there are two generations annually, with adults overwin-
tering. Clearly this is not a “typical” grasshopper, but how many other species have interesting
and unusual biology? Your field observations may help us learn the biologies of other species.

The Ecological Significance of Grasshoppers


Grasshoppers often appear to be the most abundant aboveground insects. This is especially
true in open, sunny, dry habitats such as prairies and pastures, but it also sometimes applies to
open woods, salt marshes, and disturbed areas such as crop fields. Grasshoppers exert ecologi-
cal impact and may be the dominant herbivores, or plant-feeders, in some communities.
Plant feeding by grasshoppers can deplete plant biomass and damage crops. It can shift
plant-community structure due to differential plant preference by grasshoppers. In extreme
cases, herbivory can cause ecosystem damage. This can occur directly, from disruption of
habitat by loss of vegetation, or indirectly, through increased erosion caused by reduced veg-
etation. Such habitat damage is rare, however, especially in areas with high rainfall, such as the
southeastern states.
Grasshoppers are significant due to their numbers and to their role in nutrient cycling.
Grasshoppers consume large amounts, often eating their body weight in plant tissue daily. The
consumption of plant tissue affects the relative abundance of different plant species in an area,
due to selective feeding behavior by grasshoppers. Grasshoppers also hasten the degradation
of cellulose and other materials by breaking up the plants into smaller pieces that can be
attacked by soil flora and fauna. Grasshopper fecal material, in particular, is easily degraded,
resulting in increased solubility of chemical nutrients essential for plant growth. Degradation of
fecal material and clipped foliage causes rapid release of nutrients into the soil, favoring new

5
plant growth. Without plant feeders such as grasshoppers, much of the nutrients in an area
would be bound up in dead plant tissue, insoluble, and unavailable for plant uptake. Nutrient
cycling is especially important in the warm, sandy soils commonly found in Florida, because
they are inherently nutrient-poor.
Grasshoppers are also ecologically significant because they convert plant tissue into large
“bite-sized” units of animal material, and serve as food for vertebrate animals. Animal tissue is
much more nutritious than plant material, especially for young and rapidly growing animals
which need the high levels of protein and lipids found in grasshoppers. Grasshoppers are large
enough, and abundant enough, that they attract the attention of large numbers of vertebrate
animals such as reptiles, birds, skunks, raccoons, foxes, and mice, which regularly consume
them. For insect-feeding birds, such as meadowlarks and cattle egrets, grasshoppers are often
the principal element of the diet, and their survival and reproductive efficiency may be directly
related to abundance of grasshoppers. Other species, such as kestrels and bluebirds, feed ex-
tensively on grasshoppers, but readily switch to other insects if grasshoppers are in short sup-
ply. Some birds, such as sparrows, feed heavily on vegetable matter, principally seed, but feed
their young on insects almost exclusively.
Grasshoppers are large enough and abundant enough that hunting exclusively for grasshop-
pers is an energetically efficient activity for many bird species. Grasshoppers are 50–75% crude
protein. Without grasshoppers to consume, many vertebrate animals would suffer from lack of
a suitable source of animal protein. In some parts of the world, such as sub-Saharan Africa,
grasshoppers are also a component of the human diet.
Many of Florida’s grasshoppers contribute substantially to biodiversity. In fact, 18 of the
grasshopper species found in Florida are precinctive (sometimes called endemic or indig-
enous) — found nowhere else in the world. The species unique to Florida are:

Eotettix palustris (Morse) Swamp eastern grasshopper


Eotettix signatus Scudder Handsome Florida grasshopper
Eritettix obscurus (Scudder) Obscure slantfaced grasshopper
Hesperotettix osceola Hebard Osceola’s grasshopper
Melanoplus adelogyrus Hubbell St. Johns’ spurthroat grasshopper
Melanoplus apalachicolae Hubbell Apalachicola spurthroat grasshopper
Melanoplus davisi (Hebard) Davis’ oak grasshopper
Melanoplus forcipatus Hubbell Toothcercus spurthroat grasshopper
Melanoplus gurneyi Strohecker Gurney’s spurthroat grasshopper
Melanoplus indicifer Hubbell Spinecercus spurthroat grasshopper
Melanoplus nanciae Deyrup Ocala clawcercus grasshopper
Melanoplus ordwayae Deyrup Trail ridge scrub grasshopper
Melanoplus puer (Scudder) Florida least spurthroat grasshopper
Melanoplus pygmaeus Davis Pygmy spurthroat grasshopper
Melanoplus withlacoocheensis Squitier Withlacoochee grasshopper
and Deyrup
Melanoplus symmetricus Morse Symmetrical spurthroat grasshopper
Melanoplus tequestae Hubbell Tequesta spurthroat grasshopper
Schistocerca ceratiola Hubbell and Walker Rosemary grasshopper

Thus, about 25% of Florida’s grasshoppers are unique to Florida. They are a rich biotic
resource that is not readily available to other peoples of the world. Florida’s citizens and gov-
ernment agencies that are concerned about biotic diversity should recognize the ecological
significance of this poorly known group of animals. Unlike many other groups of insects, cur-
rently there are no exotic or introduced species among Florida’s grasshoppers. Many species
of grasshoppers found in Florida have a fairly wide geographic range, often the southeastern
states or the entire area east of the Rocky Mountains.

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