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.

INSECTA Is a Taxonomic CLASS in the Phylum ARTHROPODA Basic Entomology

The Taxonomic Hierarchy is: Kingdom Animal Phylum Arthropoda Class Insecta Order Coleoptera Family Genus Species

All Arthropods Have Several Common Structural Characteristics: 1)A chitinous exoskeleton The suit of armor of this knight is somewhat analogous to the insect exoskeleton

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 members important 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 Insecta have all the characteristics of Arthropods and 3 body regions Head Thorax Abdomen

Insects also have: 3 pairs of legs (not two in spite of what you may 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 is wrong with this cartoon?

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.

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 feat for a human would be 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 in insect 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

Siphoning mouthparts are usually coiled beneath the head when not in use

Lepidoptera mouthparts video

Piercing-Sucking Mouthparts Mosquitoes, 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 on the Mesothorax and Metathorax ( never on the Prothorax).

Prothorax = no wings But 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 segments Tarsal claws

The structure of legs of insects vary depending upon use, but all have the same basic parts. Some different leg types include: RunningJumping GraspingDigging ClingingSwimming

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

Membrane Wings

Hind wings of true flies are greatly reduced and function as balancing organs called Haltares Haltare

Scale Wings

Front wings of beetles consist of hard 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 are of two types: Reproductive appendages such as genitalia or ovipositors Those not associated with reproduction

Non-reproductive appendages: Cerci Cerci on this male earwig are 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 specialized ovipositor 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 Entomology Part I