OBJECTIVES OF BASIC ENTOMOLOGYAt 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.

INSECTA

Is a Taxonomic CLASS in the Phylum

ARTHROPODA

Basic Entomology

The Taxonomic Hierarchy is:

Kingdom ----- Animal

Phylum ----- Arthropoda

Class ----- Insecta

Order ----- Coleoptera

FamilyGenus

Species

All Arthropods Have SeveralCommon Structural Characteristics:

1)A chitinous exoskeleton

The suit of armor ofthis knight is somewhatanalogous to the insectexoskeleton

All arthropods have:

2) Bilateral Symmetry

All arthropods have:

3) Jointed Appendages

All arthropods have:4) Segmented Bodies

All arthropods also have:

•A tubular digestive tract

•A dorsal tubular circulatory system

•A ventral nervous system

The Phylum Arthropoda Includes:

Chelicerata= mouthparts outside the head

Mandibulata= mouthparts inside the head

Chelicerata include some membersimportant to foresters, including

Scorpions, spiders, and ticks.

Class Arachnida

Characteristics of Arachnids include:

•All those of general arthropods

and

•2 body regions•No antennae•4 pair of walking legs

Mandibulata include:

Lobsters – Class Crustacea

Centipedes – Class Chilopoda

Millipedes – Class Diplopoda

Mandibulata also include:The Class Insecta:

Insects within the Class Insectahave all the characteristicsof Arthropods

and

•3 body regions

Head Thorax Abdomen

Insects also have:

•3 pairs of legs(not two in spite of what youmay see in some movies)

•1 pair of antennae

The other Classes (Dipoloda, Chilopda) of Arthropods do not have these last three characteristics.

So, spiders are arthropods because they have:

1) Segmented bodies

2) Jointed appendages

3) Bilateral symmetry

4) A chitinous exoskeleton

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

Knowing what you now know about Arthropods; What iswrong withthis cartoon?

Characteristics of exoskeleton and endoskeleton. Exoskeleton provides: 1) SupportLarge churches such as they have at the Air Force Academy have an external supporting structure, or exoskeletonwhich allows for large open spaces.

Exoskeleton provides: 2) Muscle attachment

Insect muscles are attached to the interior of the exoskeleton

Exoskeleton provides:3) Body covering & good protection

Exoskeleton provides:4) Water conservation.

Like the cactus, insects must conserve water

Exoskeleton provides:5) Growth restrictions, which is a problem.

Cicada Nymph

just before molting

Exoskeleton provides:

6) Good mechanical advantage

For Example: A common ordinary flea can jump about 8 inches high.A comparable featfor a human wouldbe a leap of 800 feet.

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

Structures on the Head include:

1) Antenna

2) Eyes

3) Mouthparts

1)Antenna

• These are the odor receptors of insects

• They come in a variety of forms and shapes

• They are used by entomologists ininsect identification

Filiform Antennae, crickets et al.

Lamellate Antenna – May or June Beetles

Feathery Antennae: moths, butterflies

Aristate Antennae of TseTse Fly

Genulate or “elbowed” Antenna: Ants

The Velvet Ant is not an ant! Note the antennae.

It is a wasp and also called a Cow Killer.

Plumose antennae of Male Mosquitoes

2) Eyes

• Compound Eyes

• Simple eyes called Ocelli

Compound eyes are composed of many individual eye units called Ommatidia

Compound eyes

Simple eyes - composed of 1 unit, often arranged in the shape of a triangle on adult insects

Larval insects, like caterpillars, do not have compound eyes.

But they may have numerous Ocelli with which they see reasonably well.

3)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

Chewing Mouthparts – Lady bug

•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).

•Siphoning Mouthparts

Butterflies and moths have mouthparts permanently modified into a siphoning tube

proboscus

Siphoningmouthpartsare usuallycoiled beneaththe head whennot in use

Lepidoptera mouthparts video

•Piercing-Sucking MouthpartsMosquitoes, aphids, seed bugs

•Sponging Mouthparts

Some insects, like house flies, have mouthparts modified to “sponge up” liquids

They can’t bite!

Sponging mouthpart video clip

•Cutting-Sponging Mouthparts

Horse flies and Deer flies cut a deep wound then lap up the flowing blood

The Thorax consists of three segments:

1)Prothorax

2)Mesothorax

3)Metathorax

Legs are found on all three (pro- meso- & meta-) thoracic segments.

Wings, if they occur, are found onthe Mesothorax and Metathorax (never on the Prothorax).

Prothorax = no wingsBut has 1 pair legs

Metathorax = wings &1 pair legs

Mesothorax = wings &1 pair legs

1)LEGS

Leg segments include:

• Coxa -- attached to body• Femur -- largest segment of leg• Tibia• Tarsus• Tarsal claws

Coxa Femur

Tibia Tarsal segment

s Tarsal

claws

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

Cursorial = Running legs can be found on fast moving insects, like cockroaches

Sartorial = Jumping leg of grass hopper

Raptorial Leg of Praying Mantis. Designed to grab and hold prey.

Fossorial =Digging leg of mole cricket

Sucking Louse with Clinging legs

Natatorial = Swimming

2)WINGS

There are various modifications of insect wings, some with special functions.

These include:

• Membrane Wings• Scale Wings• Haltares• Elytra• Hemi-elytra

MembraneWings

Hind wingsof true fliesare greatlyreduced andfunction as balancing organs called Haltares

Haltare

Scale Wings

Front wings of beetles consist ofhard protective covers (elytra)

True bugs (Hemiptera) have half of the wing stiff and colorful.

The other half is membraneous.

These are called “hemi elytra”.

Most insect wings have “veins”.

Wing veins have several functions:

•Carry Blood (for a short time)

•Add Strength (exoskeletal)

•Add Strength (alter shape)

•Great taxonomic value

Abdomen

The functions of the abdomen are

•Reproduction

•Excretion

Abdomen

Appendages of the abdomen areof two types:

•Reproductive appendages such as genitalia or ovipositors

•Those not associated with reproduction

Non-reproductive appendages: Cerci

Cerci on this male earwigare used for defense

Tail-like appendages on mayflies are also cerci

Reproductive: Male Scorpion Fly

Female Scorpion fly. Note absence of “stinger”

Walking sticks deposit eggs almost anywhere and do not have a specializedovipositor

Females:

•Ovipositor – is the egg laying device.Insect ovipositors vary greatly depending upon where the eggs are placed.

Giant Ichneumonid

Ovipositor 5 inches long

Some wood wasps place eggs deep in the wood. They have very well developed ovipositors.

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

End of Basic EntomologyPart I