Defining Characteristics of the Insect Orders | Entomology

Defining Characteristics of the Insect Orders | Entomology


In this video we are going to take a look
at some of the characteristics that define the different insect orders. All insects consist of the same basic anatomy. They all possess three body segments, the
head, the thorax and the abdomen, and adult insects all possess 3 pairs of legs. But each order of insect differs in one way
or another and have characteristic features that aid in differentiating each group of
insect. The first two orders are; the Zygentoma (which
are the silverfish) and the Archaeognatha (which are the jumping bristletails). Members of both orders all possess three long
caudal filaments; the lateral filaments are called cerci and the medial one is called
the epiproct. The difference between the orders is that
the cerci are nearly the same length as the epiproct in the Zygentoma whereas the cerci
are much shorter than the epiproct in the Archaeognatha. The next order is the Ephemeroptera, commonly
known as the Mayflies. Member of this order are aquatic and are characterised
by having long caudal filaments at the tip of the abdomen. They also have a single claw on each leg. They have two terrestrial winged stages, the
subimago stage and the final sexually mature imago adult stage. In these stages they have wings that are not
able to be folded over their abdomen and instead are held upright over their backs. They possess one large forewing, and the second
set of wings are either absent or much smaller in size. The next order is the Odonata, which are the
dragonflies and the damselflies. Members of the odonata are also not able to
fold their wings over their abdomen similar to the mayflies, and as such hold them outstretched
or hold them over their backs. They vary from the mayflies in that they always
have two sets of wings, where both sets of wings are of similar size. They also have long slender bodies, culminating
in a large head housing very large compound eyes and short antenna. The next order is the Orthoptera, which are
the grasshoppers and the crickets. Members of the Orthoptera characteristically
possess a set of elongated and muscular hind legs specialised for jumping. They also have mouthparts designed for biting
and chewing in addition to possessing large compound eyes. The next order are the Mantodea, which are
the mantises. Members of the Mantodea have triangular heads
with large eyes, and a flexible neck that allows the head to be swivelled. They also have enlarged raptorial forelegs
specialised for grasping prey. The next order are the Blattodea which are
the cockroaches and the termites. Cockroaches are characterised by having flattened
bodies and a large pronotum that covers most of the head. Termites are characterised by the presence
of a social system. The next order are the Phasmatodea, which
are the stick insects and leaf insects. Members of this order are adapted to be cryptic
on the plant species they are living around. Stick insects resemble twigs and branches,
whereas leaf insects resemble leaves. The next order is the Plecoptera, which are
the stoneflies. They have flattened bodies, with wings folded
horizontally over the back of their bodies. The tarsi on the hind legs are segmented into
three segments and they have long filiform antennae. The next order is the Dermaptera, which are
the earwigs. Earwigs are elongated insects characterised
by the presence of specialised cerci that have formed forcep-like pincers at the end
of the abdomen. Some possess a set of leathery forewings called
tegmen, these are short and act as coverings for the hindwings that are pleated and folded
up under the forewings. The next order is the Embioptera, which are
the webspinners. The characteristic feature of the Embioptera
is the presence of an enlarged tarsomere on the first pair of short, sturdy legs which
contain silk-producing glands. These are used to make their tubular silk
galleries in which they live. Members of this order are all small and narrow
in shape with sensitive cerci for backwards movement in the silk gallery tunnels. The next order is the Hemiptera, this order
includes an array of insects including the cicadas, aphids, planthoppers and the sheild
bugs. Members of this order possess sharp, pointed
tube-like mouthparts specialised for piercing and sucking. The suborder Heteroptera also known as the
true bugs, such as the shield bugs, have wings that are hardened at the base and sit flat
over the abdomen. The next suborder, which are the hoppers,
such as the cicadas and planthoppers, have wings that are held tent like over the abdomen. The third suborder, which include the aphids
and scale insects, have soft bodies and are often wingless. The next order is the Thysanoptera, which
are the thrips. Members of this order are small, have slender
bodies, and their heads are narrower than the thorax. Those that have wings have wings that are
rode-like and fringed. The next order is the Phthiraptera, which
are the lice. Members of this order are small, wingless
and are all parasitic. The next order are the Hymenoptera, which
are the ants, bees, wasps and sawflies. The characteristic feature of this order is
the presence of hamuli on the hindwing, hook like structures that work to lock onto the
forewing holding the two pairs of wings together. The majority of the hymenoptera (all those
except the sawflies) also characteristically possess a constricted waist. The next order is the Trichoptera, which are
the caddisflies. The characteristics feature of this order
is the presence of hairy wings that are folded roof-like over their backs at rest. The next order is the Lepidoptera, which are
the butterflies and moths. The characteristic feature of this order is
the presence of scales covering their wings and body. They also usually possess a coiled proboscis
specialised for sucking. The next order is the Diptera, which are the
flies. The characteristic feature of this order is
the presence of one set of functional wings, the forewings and hindwings that are reduced
into small mechanosensory organs called halteres. The next order is the Mecoptera, which are
the scorpionflies. The characteristic feature of this order is
the presence of a long tube-like beak with the mouthparts being on the tip. In some species the males have a distinctive
curvature of the abdomen over the back giving the appearance of a scorpion tail. The next order is the Siphonaptera, which
are the fleas. These are small insects that lack wings and
possess tube-like mouthparts adapted for piercing and sucking. The next order is the Neuroptera, which are
the lacewings. They are soft bodied insects that have four
large membranous wings that give these insects their lace like appearance. The next order is the Megaloptera, which are
the alderflies and the dobsonflies. The characteristic feature of this order is
the presence of an enlarged anal area of the hind wing, that is pleated and folds up like
a fan at rest. The next order is the Raphidioptera, which
are the snakeflies. Members of this order have an extended prothorax
giving the appearance of a long neck, and in females they have long ovipositors. They also have two pairs of wings that are
the same shape and size. The next and second to last order is the Strepsiptera,
which are the twisted-wing parasites. The characteristic feature of this order is
observed in the males and it is the twisted angle at which the hindwings are held at rest. The forewings in males are reduced to halteres. The final order is the Coleoptera, which are
the beetles. The defining characteristic of this orders
is that their forewings have adapted into hardened wing cases called elytra. Thank you for watching, if you found this
video helpful be sure to check out more of our videos.

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