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
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’)
Now if only I
could roll
into a ball…
Arthropod Class
Diplopoda
Millipedes
Millipedes
Two Pairs of Legs Per Segment
Millipede Feature –Two pairs of legs per
segment
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)
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……….