The upper lip, or _labrum_, is seen in front. Is it tapering or
expanded? In what direction is it movable? The dark pointed biting jaws
(_mandibles_) are next. Are they curved or straight? Sharp or blunt
pointed? Notched or smooth? Do they work up and down, or sideways? The
holding jaws (_maxillæ_), each with two jaw fingers (_maxillary palpi_)
are behind the chewing jaws. Why? The lower lip (_labium_) has a pair
of lip fingers (_labial palpi_) upon it. The brown tongue, usually
bathed in saliva, is seen in the lower part of the mouth. Since the
grasshopper has no lips, or any way of producing suction, it must lap
the dew in drinking. Does it merely break off bits of a grass blade, or
does it chew?
The heart, circulation, nervous system, digestive and respiratory
organs of the grasshopper agree mainly with the general description of
the organs of insects given in the next section.
=Microscopic Objects.=--These may be bought ready mounted, or may be
examined fresh. A portion of the covering of the large eye may be cut
off and the dark layer on the inside of the covering scraped off to
make it transparent. What is the shape of the facets? Can you make any
estimate of their number? A portion of the transparent hind wing may be
used, and the “veins” in it studied. A thin bit of an abdominal segment
containing a spiracle will show the structure of these important organs.
[Illustration: FIG. 115.--EGG AND MOLTS OF A GRASSHOPPER.]
=Growth of the Grasshopper.=--Some species hibernate in sheltered
places and lay eggs in the spring, but adult species are scarce at
that season. Most species lay the eggs in the fall; these withstand
the cold and hatch out in the spring. Those hatched from one set of
eggs sometimes stay together for a few days. They eat voraciously, and
as they grow, the soft skin becomes hardened by the deposit of horny
substance called chitin. This prevents further growth until the insect
molts, the skin first splitting above the prothorax. After hatching,
there are five successive periods of growth. At which molt do the very
short wings first appear? (Fig. 115.) After the last molt the animal is
complete, and changes no more in size for the rest of its life. There
has been an attempt among writers to restrict the term grasshopper
to the long-winged, slender species, and to call the shorter winged,
stouter species locusts according to old English usage.
[Illustration: FIG. 116.--COCKROACH.]
[Illustration: FIG. 117.--PRAYING MANTIS, or devil’s horse.]
[Illustration: FIG. 118.--CRICKET.]
[Illustration: FIG. 119.--MOLE CRICKET.]
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