OBJECTIVES OF BASIC ENTOMOLOGY

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OBJECTIVES OF BASIC ENTOMOLOGY At the end of this
section students should be able to 1)
Understand that due to the great diversity of
insects, and their genetic flexibility, here
will always be species causing damage to forests
and forest products. 2) Know the major
taxonomic divisions including phylum, class,
order, family, genus and species. 3) Know the
characteristics of the phylum Arthropoda and the
differences between the Chelicerata and
Mandibulata. 4) Describe the specialized
features of the class Insecta. 5) Describe the
generalized parts of the chewing mouthparts and
be familiar with the more specialized mouthpart
types found throughout the class Insecta. 6)
Describe the internal morphology of insects
particularly the features of the digestive,
respiratory, circulatory, excretory, reproductive
and nervous systems. 7) Describe the various
types of metamorphosis and give examples of
insect groups that have those types of
development. 8) Define the terms instar,
stadium, and generation in terms of insects. 9)
Know the common and order names of the insect
groups discussed in class and in the textbook.
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Basic Entomology
INSECTA Is a Taxonomic CLASS in the
Phylum ARTHROPODA
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The Taxonomic Hierarchy is
Kingdom ----- Animal
Phylum ----- Arthropoda
Class ----- Insecta
Order ----- Coleoptera
Family Genus Species
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• All Arthropods Have Several
• Common Structural Characteristics
• A chitinous exoskeleton
• The suit of armor of
• this knight is somewhat
• analogous to the insect
• exoskeleton

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All arthropods have 2) Bilateral Symmetry
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All arthropods have 3) Jointed Appendages
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All arthropods have 4) Segmented Bodies
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• All arthropods also have
• A tubular digestive tract
• A dorsal tubular circulatory system
• A ventral nervous system

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The Phylum Arthropoda Includes Chelicerata
mouthparts outside the head Mandibulata
mouthparts inside the head
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Chelicerata include some members important to
foresters, including Scorpions, spiders, and
ticks. Class Arachnida
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• Characteristics of Arachnids include
• All those of general arthropods
• and
• 2 body regions
• No antennae
• 4 pair of walking legs

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Mandibulata include Lobsters Class
Crustacea Centipedes Class Chilopoda Millipe
des Class Diplopoda
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Mandibulata also include The Class Insecta
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• Insects within the Class Insecta
• have all the characteristics
• of Arthropods
• and
• 3 body regions

Head Thorax Abdomen
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• Insects also have
• 3 pairs of legs
• (not two in spite of what you
• may see in some movies)
• 1 pair of antennae

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The other Classes (Dipoloda, Chilopda) of
Arthropods do not have these last three
characteristics.
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So, spiders are arthropods because they have 1)
Segmented bodies 2) Jointed appendages 3)
Bilateral symmetry 4) A chitinous exoskeleton
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But spiders are not insects because they
have 1) Only two body regions (not three) 2)
4 pairs of legs (not 3) 3) No antennae
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Knowing what you now know about Arthropods What
is wrong with this cartoon?
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Characteristics of exoskeleton and endoskeleton.
Exoskeleton provides 1) Support
Large churches such as they have at the Air
Force Academy have an external supporting
structure, or exoskeleton which allows for large
open spaces.
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Exoskeleton provides 2) Muscle attachment
Insect muscles are attached to the interior of
the exoskeleton
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Exoskeleton provides 3) Body covering good
protection
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Exoskeleton provides 4) Water conservation.
Like the cactus, insects must conserve water
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Exoskeleton provides 5) Growth restrictions,
which is a problem.
Cicada Nymph just before molting
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Exoskeleton provides 6) Good mechanical
advantage For Example A common ordinary flea
can jump about 8 inches high. A comparable
feat for a human would be a leap of 800 feet.
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All Insecta have 3 body regions which are called
Tagma Tagma are groups of segments that function
together to perform a general task.

• Head perception, food intake
• Thorax locomotion, food processing
• Abdomen reproduction, excretion

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• Structures on the Head include
• Antenna
• 2) Eyes
• 3) Mouthparts

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• Antenna
• These are the odor receptors of insects
• They come in a variety of forms and shapes
• They are used by entomologists in
• insect identification

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Filiform Antennae, crickets et al.
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Lamellate Antenna May or June Beetles
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Feathery Antennae moths, butterflies
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Aristate Antennae of TseTse Fly
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Genulate or elbowed Antenna Ants
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The Velvet Ant is not an ant! Note the
antennae. It is a wasp and also called a Cow
Killer.
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Plumose antennae of Male Mosquitoes
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• Eyes
• Compound Eyes
• Simple eyes called Ocelli

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Compound eyes
Compound eyes are composed of many individual
eye units called Ommatidia
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Simple eyes - composed of 1 unit, often arranged
in the shape of a triangle on adult insects
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Larval insects, like caterpillars, do not have
compound eyes. But they may have numerous Ocelli
with which they see reasonably well.
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1. Mouthparts Insects have much variation in
   mouthparts, depending upon food habits and
   include

• Chewing -- grasshoppers, beetles, Lepidoptera
  larvae,
• Chewing-lapping -- bees
• Siphoning -- Butterflies
• Piercing-Sucking -- aphids, mosquitoes, scale
  insects, leafhoppers
• Sponging -- house flies
• Cutting-Sponging -- Deer flies, horse flies

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Chewing Mouthparts Lady bug
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• Chewing-Lapping Mouthparts
• Some insects, like honey bees, have normal
  mandibles but other structures are modified into
  
• sucking lapping devices.

Honeybees use their sucking mouthparts to collect
nectar and their chewing mouthparts to chew and
create waxy combs to store their nectar (honey).
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• Siphoning Mouthparts
• Butterflies and moths have mouthparts
  permanently modified into a siphoning
• tube

proboscus
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Siphoning mouthparts are usually coiled
beneath the head when not in use
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Lepidoptera mouthparts video
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• Piercing-Sucking Mouthparts
• Mosquitoes, aphids, seed bugs

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• Sponging Mouthparts
• Some insects, like house flies, have
• mouthparts modified to sponge
• up liquids
• They cant bite!

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Sponging mouthpart video clip
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• Cutting-Sponging Mouthparts
• Horse flies and Deer flies cut a deep wound then
  lap up the flowing blood

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• The Thorax consists of three segments
• Prothorax
• Mesothorax
• Metathorax

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Legs are found on all three (pro- meso- meta-)
thoracic segments. Wings, if they occur, are
found on the Mesothorax and Metathorax (never on
the Prothorax).
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Prothorax no wings But has 1 pair legs
Metathorax wings 1 pair legs
Mesothorax wings 1 pair legs
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• LEGS
• Leg segments include
• Coxa -- attached to body
• Femur -- largest segment of leg
• Tibia
• Tarsus
• Tarsal claws

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Coxa
Tarsal segments
Tibia
Femur
Tarsal claws
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The structure of legs of insects vary depending
upon use, but all have the same basic parts.
Some different leg types include
Running Jumping
Grasping Digging
Clinging Swimming
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Cursorial Running legs can be found on fast
moving insects, like cockroaches
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Sartorial Jumping leg of grass hopper
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Raptorial Leg of Praying Mantis. Designed to
grab and hold prey.
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Fossorial Digging leg of mole cricket
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Sucking Louse with Clinging legs
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Natatorial Swimming
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• WINGS
• There are various modifications of insect wings,
  some with special functions. These include
• Membrane Wings
• Scale Wings
• Haltares
• Elytra
• Hemi-elytra

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Membrane Wings
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Hind wings of true flies are greatly reduced
and function as balancing organs called
Haltares
Haltare
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Scale Wings
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Front wings of beetles consist of hard protective
covers (elytra)
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True bugs (Hemiptera) have half of the wing
stiff and colorful. The other half is
membraneous. These are called hemi elytra.
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Most insect wings have veins.
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• Wing veins have several functions
• Carry Blood (for a short time)
• Add Strength (exoskeletal)
• Add Strength (alter shape)
• Great taxonomic value

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• Abdomen
• The functions of the abdomen are
• Reproduction
• Excretion

Abdomen
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• Appendages of the abdomen are
• of two types
• Reproductive appendages such as
• genitalia or ovipositors
• Those not associated with
• reproduction

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Non-reproductive appendages Cerci
Tail-like appendages on mayflies are also cerci
Cerci on this male earwig are used for defense
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Reproductive
Male Scorpion Fly
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Female Scorpion fly. Note absence of stinger
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• Females
• Ovipositor is the egg laying device.
• Insect ovipositors vary greatly depending upon
  where the eggs are placed.

Walking sticks deposit eggs almost anywhere
and do not have a specialized ovipositor
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Giant Ichneumonid
Some wood wasps place eggs deep in the wood.
They have very well developed ovipositors.
Ovipositor 5 inches long
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Some insects have the ovipositor modified as a
defensive weapon. The stinger of honey bees is a
modified ovipositor.
Honey bee pulling away from sting
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End of Basic Entomology Part I