An Introduction

to “Bugs”

Whitney Cranshaw

Colorado State University

An Introduction

to “Bugs”

Whitney Cranshaw

Colorado State University

Arthropod Features

• Segmented body

• Exoskeleton

• Jointed appendages

• Bilateral symmetry of design

• Dorsal heart/Ventral nerve cord

Arthropod Characteristics

Segmented bodies

Segmented worms (annelids)

Onchyphorans (velvet worms)

Arthropods (insects, arachnids,

crustaceans, etc.)

Arthropods – and some other animals – have

segmented bodies

Phylum Arthropoda

Arthropods

Arthropod Characteristics

Segmented bodiesExternal Skeleton

(Exoskeleton)

Features of the Insect Exoskeleton

Protection from:

-Pathogens

-Physical trauma

-Insecticides, etc.

Eleodes darkling

beetles

(aka “stink beetles”.

“skunk beetles”,

“circus beetles”)

Primary advantage of an exoskeleton:

Provides a means for small animals to avoid

excessive water loss!

Allows for development of:

-Appendages

Features of the Insect Exoskeleton

Mobility is enhanced.

Allows for development of:

-Appendages

-Specialized structures

Features of the Insect Exoskeleton

Enhance feeding, defense,

movement

Allows for development of:

-Appendages

-Specialized structures

-Arthropod tracheal system of

gas exchange

Features of the Insect Exoskeleton

Decreased water loss

The exoskeleton allows

for development of the

arthropod tracheal system

of gas exchange

Spiracles

The exoskeleton allows

for development of the

arthropod tracheal system

of gas exchange

Spiracle

Disadvantage of an exoskeleton:

9:11

10:36

11:42

Darkening of a recently

molted lady beetle adult

Soft Shell vs. Hard

Shell Lobster Meat

Extraction Trial

July 2015

Soft shell Hard shell

Meat Extraction Soft Shell vs. Hard Shell

Water Component Soft Shell vs. Hard Shell

Soft shell Hard shell

Arthropod Characteristics

Segmented bodiesExternal Skeleton

(Exoskeleton)

Jointed

appendages

Arthropod Characteristic

Body plan is

bilaterally

symmetrical

Incorrect

I YOU

A Cricket’s Valentine

Arthropod Features

• Segmented body

• Exoskeleton

• Jointed appendages

• Bilateral symmetry of design

• Dorsal heart/Ventral nerve cord

Classes of

Arthropoda

Crustaceans

Arthropod Class

Terrestrial Isopods*

(Sowbugs and Pillbugs)

*Subphylum Crustacea ; Class Malacostraca; Order

Isopoda

Crustacean Features

• Two pair of

antennae

• 7 pair appendages

• Distinct head area

• Body usually

covered by a shield

like carapace

• Oxygen acquired

through gills

Seven pairs of legs Mouthparts

Immature stages of sowbugs and

pillbugs are similar in features as

the adults, but smaller – a simple

type of metamorphosis

Sowbug

Molting

Front half molts first

Back half molts second

Molting occurs in

two stages with the

sowbugs and

pillbugs

Sowbugs

Pillbug (a.k.a.

“roly-poly’)

Sowbugs

Now if only I

could roll

into a ball…

Pillbug

Arthropod Class

Diplopoda

Millipedes

Millipedes

Two Pairs of Legs Per Segment

Millipede Feature –Two pairs of legs per

segment

Duff Millipedes

Arthropod Class

Chilopoda

Centipedes

Basic Features of Centipedes

1 Pair Antennae

1 Pair Legs/Body

Segment

Most

centipedes

have 15 to 23

pairs of legs

Head

Pseudohead

Centipedes

Maxillipeds

Prey is captured with the

maxillipeds and are injected

with a toxin (cytolysin)

Stone Centipede – A common garden resident

Tiger Centipede(Giant Desert Centipede)

House Centipede

Orders of

Arachnids

Arachnid Feature – Two Body Regions

Cephalothorax

Abdomen

Arachnid Feature – Four Pairs of Legs

Chelicerae

Face of a longjawed spider showing chelicerae and pedipalps

PedipalpsPhoto courtesy of Brian Valentine

Spiders Order Araneae

Some spiders use

webbing to snare prey

Some spiders

hunt prey without

the aid of silk

David Cappaert

Brian Valentine

Daddy longlegs, Harvestmen

Order: Opiliones

Mites & Ticks Order Acari

Ticks feed on the blood of

vertebrates

Scorpions Order Scorpiones

Pedipalps (chelae)

for prey capture

Scorpion chelicerae (jaws)

Stinger used for defense

Scorpions

fluoresce in

ultraviolet

light

Scorpions fluorescing

under black light

An adorable baby scorpion!

Common

striped bark

scorpion

Centruroides vittatus

Sunspiders, Windscorpions,

Solpugids

Order Solifugae

Courtesy University

of California

The notorious “camel spider” photograph

Orders of Insects

Segmented

Body

External skeleton/

Exoskeleton

Jointed

Appendages

Arthropod Characteristics

Abdomen Thorax Head

1954

Academy Award

Nominee for Special

Effects

Head

Thorax Abdomen

Three pairs of legs – on the thorax

Larvae of Lepidoptera,

known as caterpillars,

have 2-5 pairs of

abdominal prolegs

The prolegs are tipped

with hook-like crochets

Lepidoptera larvae (caterpillars) have prolegs on

the abdomen

Inchworms and loopers have only 2 or 3 pairs of prolegs

Whitelined sphinx (Hyles

lineata) – The common

“hummingbird moth” of

the western US

Orders of Insects

How Many Kinds of Insects

Are There on Earth?

• Approximately 1 million different

insect species have been described

• It is estimated that there presently

exist probably 4-6 million species of

insects; some estimates are higher

• New species of insects are described

at a rate of about 7200/year

New species are

being identified all

the time

How Many Individual

Insects Are There on Earth?

About 250 million for

every human (mushy guess)

How Many Individual

Insects Are There on Earth?

Insect comprise about 80

percent of the biomass of

land animals

The 4 Rs

Reading

The 4 Rs

Reading

WRiting

The 4 Rs

Reading

Writing

ARithmetic

The 4 Rs

Reading

Writing

Arithmetic

Arthropods!

Metamorphosis

‘Change in form’

A simple, or gradual pattern of metamorphosis

Mosquito Life Cycle

Adult (left)

Larvae/wrigglers (lower left)

Pupae/tumblers (below)

Next up:

Natural

Enemies of

Insect

Pests

What Should We Cover?

• Hummingbird Moths

• Yellowjackets and

Hornets

• Whiteflies

• Slugs

• Earwigs

• Wood borers

• Bark beetles

• Japanese beetle

• Emerald ash borer

• Aphids

• Scale insects

• Spider mites

• Gall insects

• Nuisance invaders

• Grasshoppers

• Codling Moth

• Flea beetles……….