The document provides extensive information on arthropods, focusing on their classification, structure, and life cycles, highlighting the vast diversity and ecological significance of insects. It covers different classes, particularly insects and arachnids, detailing their physical characteristics, reproductive methods, and internal systems. It also discusses the estimated number of species and variations in the life cycle, including ametabolous, hemimetabolous, and holometabolous development.

1. Insect Pest ID and Life
Cycle
LNT 136 – Spring 2017
Mark Valen

2. Invertebrate Pests
Arthropods (Phylum) – invertebrates with
exoskeletons, a segmented body, and jointed
appendages

3. Arthropods
Arthropod species are estimated to be between
1,170,000 and 5 to 10 million and account for over
80% of all known living animal species
• Small size, in many cases
• Flight
• Adaptability
• Mutation
• Exoskeleton

4. Exoskeleton
• AKA cuticle made of chitin
• May have brustles called setae
• May act as sensors to detect air currents, or contact with
objects;
• Aquatic insects, which are air‐breathers, use thick felt‐
like coats of setae to trap air, extending the time they
can spend under water; heavy, rigid setae serve as
defensive spines.
• All arthropods use muscles attached to the inside
of the exoskeleton to flex their limbs, but some also
use hydraulic pressure to extend them (i.e. spiders)

5. Segmentation
• Insects
• Head
• Thorax
• Abdomen
• Arachnids
• Cephalothorax
• Abdomen

6. Arachnids
• Arachnids (class) have eight legs, live mainly on
land, and comprise over 100,000 named species
• spiders
• scorpions
• harvestmen
• ticks
• mites
• solifuges

7. Myriapoda
• Millipedes
• 2 pairs of jointed legs on body segments
• Poisonous
• Slow Moving
• Detritivores
• Centipedes
• 1 pair of legs per body segment
• Venomous
• Fast Moving
• Carnivores

8. Insects
• Insects (class) contain six legs, compound eyes, and one
pair of antennae
• Most species‐rich member of all ecological guilds
• Insects may be found in a wide variety of environments:
• polar ice caps
• oil slicks
• salt water
• thermal pools
• hot desert sands

9. Insects
• Mean estimate of 5.5 million species.
• About 850,000–1,000,000 of all described species
are insects.
Comparison of the estimated number of species in the four most speciose insect orders
Described species
Average description
rate
(species per year)
Publication effort
Coleoptera 300,000–400,000 2308 0.01
Lepidoptera 110,000–120,000 642 0.03
Diptera 90,000–150,000 1048 0.04
Hymenoptera 100,000–125,000 1196 0.02

10. Coleoptera
Beetles
Front pair of wings hardened into wing‐cases

11. Diptera
True Flies (Blow flies, mosquitos, hover flies)
Single pair of wings to fly
Mobile head, with a pair of large compound eyes, and
mouthparts designed for piercing and sucking

12. Hymenoptera
Wasps, Bees, Ants
Females typically have a special ovipositor for inserting
eggs into hosts or otherwise inaccessible places.
The ovipositor is often modified into a stinger

13. Lepidoptera
Moths and Butterflies

14. Basic Insect Structure
• Head – 0‐5 eyes, Antennae, Mouth parts

15. Basic Insect Structure
• Thorax
• Three segments, each having a set of spiracles.
• Six legs.
• 1‐2 pairs of wings.

16. Basic Insect Structure
• Abdomen
• 11 segments
• A pair of spiracles on each segment.
• Body portion on which you would find stingers,
ovipositors.

17. Life Cycle
• No Metamorphosis (Ametabolous)
• Begin as eggs, hatch to become immatures, and develop
on into adults. Immatures look identical to adults but
smaller in size.

18. Life Cycle
• Incomplete Metamorphosis (Hemimetabolous)
• Egg
• Often encased
• Nymph
• Looks like small adult
• Sheds or molts to grow to next stage
• Adult
• Primary goal is reproduction

19. Life Cycle
• Complete Metamorphosis
• Holometabolous
• Egg
• Larva (EATING)
• Pupa (NON FEEDING)
• Adult (REPRODUCTION)

20. Internal Structure
• Digestive System
• Runs the full length of
the body. Includes:
• Mouth (pharynx and
esophagus)
• Crop
• Gizzard
• Large intestine/small
intestine
• Rectum
• Anus

21. Internal Structure
• Circulatory System
• Open system.
• ‘Blood’ moves from areas of high pressure to
low pressure.
• Blood does not carry oxygen.
• Multi‐chambered heart.
• Carries nutrients to all body tissues.
• Blood color: Blue‐Green/Grey
• Cold blooded.

22. Internal Structure
• Nervous System
• Brain = central ganglia in
the head.
• Additional ganglia are
attached to the central
ganglia, and one runs to
each body segment.

23. Internal Structure
• Respiratory System
• Each abdomen/thorax
segment has a pair of
spiracles.
• The spiracles are
connected by tracheae.
• Move oxygen throughout
the body.