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ORTHOPTERA 89
ments are visible. Often the ninth sternum of the male bears a pair of anal
styli. There are two thoracic and eight abdominal pairs of spiracles. The females
of the locusts, grasshoppers, sand crickets, and mole crickets have inconspicuous
ovipositors, while the katydids, crickets, cave crickets, and tree
crickets have prominent sword-like, sickle-shaped, or spear-shaped ovipositors
which make them easily recognizable and serve to place the eggs in the soil or
into the tissues of leaves, stems, or limbs of plants. Long or short simple or
jointed cerci are also present at the tip of the abdomen.
The stridulating or sound-producing organs and auditory organs of this
order are quite highly developed and rather unusual among insects. They are
more fully discussed under the various families.
The coloration is normally cryptic. matching or mimicking the immediate
surroundings. The ground-inhabiting forms are usually various shades of gray,
drab, brown, yellow, or black. Grass- and plant-feeding species are frequently
green or various combinations of bright colors. The hind wings are also frequently
bright red, yellow. orange, blue, or even black. Nocturnal forms, like
the common field crickets, are black or brown, although nocturnal cave and
camel crickets may be of combinations of very pale colors.
Internal anatomy. - These typically biting, herbivorous insects have strong
mouth parts and naturally a well-developed digestive system in which the
ccsophagus expands into an ample crop leading into a specialized type of gizzard
(wanting or vestigial in the LOCUSTIDtE). The mid-intestine is long and
convoluted in the TETTIGONIIDLE and GRYLLIDlE and straight with
longitudinal plaits in the LOCUSTIDrE. There are six enteric c;;eca. each with a
short posterior diverticulum, in the LOCUSTIDlE and two sac-like creca in
the TETTIGONIIDLE and the GRYLLIDJE. The Malpighian tubules are
arranged in bundles in the LOCUSTIDJE, capillary and opening in groups at
the tops of small papi1lre in the TETTIGONIIDlE, and in a single bundle discharging
into the common duct in the GRYLLIDlE.
The nerve centers consist of three thoracic and normally five or six and rarely
four abdominal ganglia. In some of the locusts the tracheal system has a series
of air sacs of which a large pair is located in the thorax and five pairs in the
abdomen. The reproductive organs are far too variable to be adequately treated
here, and the reader is referred to works on anatomy for this information.
Practically all species are oviparous, but the shape and structure of the eggs
and the manner and place of their deposition is exceedingly varied and are discussed
under the families, as are also the more generalized types of life histories
and habits. There are about 21,000 speCies in this group, including those of the
orders BLATTARIA, PHASMIDA, MANTODEA, and other orthopteroid
groups.
KEY TO SUBORDERS
1. Antennre setifonn, short, usually much shorter than the body; auditory
organ, when present, near the base of the abdomen and often par·
tially or wholly covered by the base of the wings; ovipositor mean·