| What are Insects? Insects Home |
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For Parents/Educators you are very welcome to download any or all of our Grade K-5 Thematic Units and/or Lesson Plans for use in your homes,
homeschool, classroom or community centres.
IN undertaking a study of insects it is well first of all to know something about what they are, their general nature, appearance, habits and
development. The insects comprise the largest group of animals on the globe. There are about four times as many different kinds of insects as
all other kinds of animals combined. Insects vary greatly in size. Some are as large as small birds, while others are so small that a thousand
placed in one pile would not equal the size of a pea.
Insects are commonly spoken of as "bugs." This term, however, is properly used only when referring to the one order of insects which includes
the sap and blood-sucking insects such as the chinch bug, bed-bug, squash bug, and the like. Then too, there are many so-called "bugs" which
are not insects at all. Spiders, thousand-legs, crawfishes and even earthworms are often spoken of as bugs.
Side view of grasshopper with wings and legs partly removed. Note the division of the body into head, thorax, composed of prothorax, mesothorax and metathorax, and
abdomen consisting of ring-like segments.
Insects are variously formed, but as a rule the mature ones have three and only three pairs of legs, one pair of feelers, one pair of large eyes,
and one or two pairs of wings. The body is divided into a head, thorax and abdomen. The head bears the eyes, feelers and mouth, the thorax
bears the legs and wings, and the abdomen is made up of a number of segments. The presence of wings at once decides whether or not it is
an insect, for, aside from bats and birds, insects alone have true wings. These are the distinguishing characters of the full grown insect, but,
like birds, they hatch from eggs and while young do not always look like their parents. When young they may take on various shapes as
caterpillars, borers, maggots, grubs, hoppers, and the like. Young insects are often difficult to distinguish from true worms, centipedes, snails,
and such forms, but after one has collected and reared some of the young and watched them pass through the different stages and emerge with
wings they are much more easily recognised.
Young insects as a rule are soft like caterpillars and maggots, while the old ones usually have a hard body wall, similar to the beetles and
wasps. The wings are usually thin and transparent though in some cases they are leathery or hard as in case of beetles or covered with scales
as in the butterflies. The three pairs of legs are jointed and used for running, climbing, jumping, swimming, digging or grasping. The feelers or
antennae are usually threadlike, clubbed, or resemble a feather and extend forward or sidewise from the head. The large eyes are compound,
being made up of many great small units which, when magnified, resemble honey-comb. In some cases two or three small bead-like eyes may
be present besides the two large eyes. The mouth parts of insects may be formed for chewing, as in the grasshopper, or for sucking up liquids,
as in the mosquito. The mouth of an insect is built on an entirely different plan from our own. Chewing insects have an upper and lower lip and
between these there are two pairs of grinding jaws. These jaws are hinged at the side of the face and when chewing they come together from
either side so as to meet in the middle of the mouth. They therefore work sidewise rather than up and down. The mouth parts of the sucking
insects are drawn out to form a sucking tube or proboscis as in case of the butterfly or mosquito.
For Parents/Educators you are very welcome to download any or all of our Grade K-5 Thematic Units and/or Lesson Plans for use in your homes,
homeschool, classroom or community centres.
IN undertaking a study of insects it is well first of all to know something about what they are, their general nature, appearance, habits and
development. The insects comprise the largest group of animals on the globe. There are about four times as many different kinds of insects as
all other kinds of animals combined. Insects vary greatly in size. Some are as large as small birds, while others are so small that a thousand
placed in one pile would not equal the size of a pea.
Insects are commonly spoken of as "bugs." This term, however, is properly used only when referring to the one order of insects which includes
the sap and blood-sucking insects such as the chinch bug, bed-bug, squash bug, and the like. Then too, there are many so-called "bugs" which
are not insects at all. Spiders, thousand-legs, crawfishes and even earthworms are often spoken of as bugs.
Side view of grasshopper with wings and legs partly removed. Note the division of the body into head, thorax, composed of prothorax, mesothorax and metathorax, and
abdomen consisting of ring-like segments.
Insects are variously formed, but as a rule the mature ones have three and only three pairs of legs, one pair of feelers, one pair of large eyes,
and one or two pairs of wings. The body is divided into a head, thorax and abdomen. The head bears the eyes, feelers and mouth, the thorax
bears the legs and wings, and the abdomen is made up of a number of segments. The presence of wings at once decides whether or not it is
an insect, for, aside from bats and birds, insects alone have true wings. These are the distinguishing characters of the full grown insect, but,
like birds, they hatch from eggs and while young do not always look like their parents. When young they may take on various shapes as
caterpillars, borers, maggots, grubs, hoppers, and the like. Young insects are often difficult to distinguish from true worms, centipedes, snails,
and such forms, but after one has collected and reared some of the young and watched them pass through the different stages and emerge with
wings they are much more easily recognised.
Young insects as a rule are soft like caterpillars and maggots, while the old ones usually have a hard body wall, similar to the beetles and
wasps. The wings are usually thin and transparent though in some cases they are leathery or hard as in case of beetles or covered with scales
as in the butterflies. The three pairs of legs are jointed and used for running, climbing, jumping, swimming, digging or grasping. The feelers or
antennae are usually threadlike, clubbed, or resemble a feather and extend forward or sidewise from the head. The large eyes are compound,
being made up of many great small units which, when magnified, resemble honey-comb. In some cases two or three small bead-like eyes may
be present besides the two large eyes. The mouth parts of insects may be formed for chewing, as in the grasshopper, or for sucking up liquids,
as in the mosquito. The mouth of an insect is built on an entirely different plan from our own. Chewing insects have an upper and lower lip and
between these there are two pairs of grinding jaws. These jaws are hinged at the side of the face and when chewing they come together from
either side so as to meet in the middle of the mouth. They therefore work sidewise rather than up and down. The mouth parts of the sucking
insects are drawn out to form a sucking tube or proboscis as in case of the butterfly or mosquito.
◄◄Face of grasshopper enlarged showing parts;
ant., antenna; eye, compound eye; oc., ocellus or
simple eye; cl., clypeus; lbr., labrum or upper lip; mx.
p., maxillary palpus; lb. p., labial palpus; lab.,
labium or lower lip.
ant., antenna; eye, compound eye; oc., ocellus or
simple eye; cl., clypeus; lbr., labrum or upper lip; mx.
p., maxillary palpus; lb. p., labial palpus; lab.,
labium or lower lip.
| Mouth parts of grasshopper shown in relative position; lbr., labrum; md., mandibles; hyp., hypopharynx; max., maxillae; lab., labium.►► |
Leg of grasshopper showing segmentation. The
basal segment c, is the coxa, the next t, the
trochanter, the large segment f, the femur, the
long slender one ti, the tibia, and the three
jointed tarsus ta, with claws at the tip.►►
basal segment c, is the coxa, the next t, the
trochanter, the large segment f, the femur, the
long slender one ti, the tibia, and the three
jointed tarsus ta, with claws at the tip.►►
The internal organs of insects are similar to those of other animals. The digestive tube consists of oesophagus, gizzard, or stomach, and
intestines. The nervous system is well developed as shown by the extreme sensitiveness of insects to touch. The brain is comparatively
small except in the bees and ants. The circulatory system consists simply of a long tube heart, the blood vessels being absent. In this way
the internal organs of the insect are simply bathed in the blood. The system of respiration is most complicated. The air is taken in through
pores usually along the side of the body and is then carried through fine tracheal tubes to all parts of the body. You cannot drown an insect by
putting its head under water, since it does not breathe through its mouth. The muscular system is similar to that of other animals which have
the skeleton on the outside.
intestines. The nervous system is well developed as shown by the extreme sensitiveness of insects to touch. The brain is comparatively
small except in the bees and ants. The circulatory system consists simply of a long tube heart, the blood vessels being absent. In this way
the internal organs of the insect are simply bathed in the blood. The system of respiration is most complicated. The air is taken in through
pores usually along the side of the body and is then carried through fine tracheal tubes to all parts of the body. You cannot drown an insect by
putting its head under water, since it does not breathe through its mouth. The muscular system is similar to that of other animals which have
the skeleton on the outside.
The internal organs of the honey bee. Note the strong wing muscles in the thorax. The tube-
like heart begins in the head and extends back through the thorax and follows the curve of
the abdomen. Below the heart is the digestive tube consisting of the slender oesophagus
which extends back to the expanded honey stomach, in which the bee carries the nectar it
collects from flowers, then the curled true stomach, the small intestine and expanded large
intestine. Below this is the nervous system consisting of the brain and a chain of connected
enlargements or ganglia extending back into the abdomen in the lower part of the body.
The respiratory system in part appears just above the honey stomach, and the black
circular or oval spots are cross sections of connecting air tubes, which run all through the
body. Also note the sting with the poison gland and sack which are pulled out with the sting;
also the sucking tube for getting honey from flowers, and the structures on the legs for
gathering and carrying pollen; the pollen basket is on the back side of the hind leg.►►
Their Methods of Developing
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