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.
[Illustration:
FIG. 115.—EGG AND MOULTS OF A GRASSHOPPER.
]
=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.
=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 retards further growth until the insect moults, the skin
first splitting above the prothorax. After hatching, there are five
successive periods of growth. At which moult do the very short wings
first appear? (Fig. 115.) After the last moult 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 family, and to call the shorter winged, stouter
family 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.
]
[Illustration:
FIG. 120.—FRONT LEG OF MOLE CRICKET. × 3.
]
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