Introduction to Insects
Entomology Training
for
Master Gardeners
THE INSECTS
• Fossil
records indicate insects on land more
than 300 million years ago
Insects are from an ancient lineage that included trilobites
and other arthropods which were abundant in the oceans
over 500 million years ago.
Trilobites are extinct... but we are surrounded by
other arthropods.
Insects are in the phylum Arthropoda
(“jointed leg”)
The phylum is divided into 6 smaller groups called
classes:
 Crustacea (crabs, lobsters, shrimps)
 Chilopoda (centipedes)
 Diplopoda (millipedes)
 Symphyla (symphylans)
 Arachnida (spiders, mites)
 Insecta (insects)
All arthropods share the following
characteristics:
1) Arthropods have a segmented body
2) All arthropods have paired, jointed legs
3) All arthropods have a chitinous exoskeleton
(which is periodically shed and renewed as the animal grows)
University of Nebraska-Lincoln, Department of Entomology, Leon Higley
4) All arthropods have a digestive system
(tube that runs from head to tail)
5) All arthropods have an “open” circulatory system,
no veins, arteries etc. Blood is held in a dorsal tubular structure
with lateral openings in the abdomen.
6) All arthropods have a ventral nervous system which consists of a
tiny brain, paired nerve cords which extend from the brain backward,
and nerve centers called ganglia.
7) All arthropods breathe by means of gills, or tracheae and spiracles.
8) Separate sexes (nearly always)
The Class Crustacea (lobster, shrimp, crab, pillbugs,
etc.) have two pairs of antennae and at least five pairs
of legs.
Yummy!
The classes Chilopoda, Diplopoda, and Symphyla
(centipedes, millipedes, etc.) have antennae,
many legs and only two body regions.
They add segments as they molt.
The class Arachnida have 8 legs and no antennae.
They are in a group of Arthropods that diverged from
the insects in the mid-paleozoic.
The Class Insecta
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
(Class: Arachnida)
At least half (50%-80% [?]) of the animal species
currently occupying the earth are insects
(approximately 1.5 million different animal species)
More than 1 million species of
insects world-wide
Over 13,000 species of
insects known from Florida
New species appear almost daily due to
shipments of plants and other materials
into Florida from abroad
Of all insect species in the world
Less than 1%
Considered
to be pests
Beneficial or just co-exist
(> 99%)
Relation of insects to humans:
1. Beneficial: Pollination, break down raw materials,
aerate soil, bio-control of weeds and bad bugs, food for
many animals, medical uses.
2. Aesthetic Value: Butterflies
3. Injurious: Feed on plants, stored foods, woods, fabrics,
humans, and animals
The Insects
1. Three, usually distinct body regions
(head, thorax, and abdomen)
2. One pair of segmented antennae
3. Usually have one pair of compound eyes
4. Three pairs of legs
5. Two pair of wings usually (some have only
one pair (i.e., flies) or no wings at all).
The Head. Functions mainly for feeding and
sensory perception.
The Thorax. Responsible for locomotion.
Made up of 3 segments. A pair of legs arise
from each segment. Wings, if present, arise from
2nd and 3rd segment.
The Abdomen is responsible for excretion and reproduction.
Growth and Develoment
Metamorphosis - The process of change from egg to adult.
Incomplete or gradual metamorphosis. Baby insects
(nymphs) look similar to adults (grasshoppers, aphids,
cockroaches). Growth occurs through molting.
Complete metamorphosis. Larvae look nothing like adults.
The larvae pass through a pupal stage to change into the
adult form (wasps, beetles, moths, butterflies, flies).
How Insects Feed
Insects can be separated by the type
of mouthparts they possess which
dictates the type of job they have.
Most common type
of mouthpart is
chewing.
Tear off pieces of
tissue and eat it.
Plant damage caused by
pests with chewing mouthparts
Some common yard and garden pests
with chewing mouthparts
“Skeletonizing” damage caused by immature chewing insects
Immature beetles
Another common type of mouthpart is
piercing/sucking
(This is a
good bug)
Plant damage caused by
pests with piercing/sucking mouthparts
Whiteflies – Bad insects
A few good bugs that eat whiteflies
Big-eyed Bugs
Minute Pirate Bug
Some specific insects Florida
Master Gardeners should know …
Orange Dog Caterpillar – Bad insect (?)
Aphids
Some Things
That Eat
Aphids
(Good Insects)
Lady Beetles- eggs,
adult, pupae, and
larvae
Lacewing - eggs and adult
Lacewing larvae
Aphid Mummies
Parasitic Wasps
Mole Crickets
Mole Cricket Damage
Tropical Sod Webworm
Chinch Bugs
Enemies of
Lawn Pests
Rove Beetles
Earwig
Big-eyed Bug
Stinkbugs
Note spines on thorax
Green Stinkbug - Bad
Predatory Stinkbug - Good
Parasitic wasps
Predaceous
Stinkbug
Leafminers – Feed within the leaf
Serpentine Leaf Miner
Citrus Leaf Miner
Lacebugs
(Note: Black dots of excrement on
leaf undersides)
Southern Pine Beetle – Tree boring Beetle
Leaf-eating Beetles
Thrips
Rasping-sucking
mouthpart
Mealybugs
UF - IFAS
Twospotted Spider Mite
Spider-Mite Webbing
UF - IFAS
Predatory Mite (eats bad mites)
Armored Scales: Florida Red Scale
UF, IFAS
Scale Insects
Asian Cycad Scale
Soft Scale: Green Scale
UF - IFAS
Scale predators
and parasites
Lady Beetle Species
Parasitic Wasps
Adapted by Jim Price from:
Author: Tom Weissling, University of Florida
Photos:
University of Florida
University of Nebraska
University of California
Entomology And Nematology Department
Copyright University of Florida 2000
For more detailed information see the Featured
Creatures WWW site at
http://www.ifas.ufl.edu/~insect/