1. Insect Biology
February 4, 2008

2. Development Ametabolous Development Hemimetabolous Development
Holometabolous Development

3. Abdomen 9-11 segments Dorsal tergum, ventral sternum
8 segments with spiracles
Genitalia, cerci

4. Digestive System Alimentary canal
Water+food--enzymes-->absorbable molecules+energy+wastes

5. Circulatory System Open Hemolymph 5-40% of body weight
Hemocoel--body cavity
Dorsal vessel

6. Respiratory System
Insects need oxygen
Spiracles, trachea

9. Holometabolous Big change from larva to adult Wings develop internally
Undergo pupal stage to form adult
Pupa: non-feeding, generally immobile intermediate stage between larvae and adult

10. All insects start as eggs
Wide variety of forms
Eggs

11. Larval/Nymph Stages Ametabolous/hemimetabolous young: nymphs
Nymph: immature insect with external wingpads
Naiad: immature insect with external wingpads and gills
Holometabolous young: larvae
Larva: immature insect with internally-developing wingpads

12. Larval Stages
Instars
4-6

13. 3 PAIRS LEGS, WELL DEVELOPED HEAD, CHEWING MOUTHPARTS
ABDOMINAL PROLEGS, SCLEROTIZED HEAD, CHEWING MOUTHPARTS
LACK ALL TRUNK APPENDAGES, HEAD CAPSULE VARIES
ADAPTED FOR MINING IN SOIL, MUD, ANIMAL OR PLANT TISSUES

14. Pupa Erroneously called “resting stage” Breakdown/buildup of body
Can last a long time--dies when runs out of energy
Used to survive harsh conditions

16. When sexually mature
Imago (Adult)

18. Ametabolous Orders Thysanura Thysan-fringed -ura tail
Mandibulate mouthparts
Three caudal appendages
Long segmented antennae
Common members: Silverfish, firebrats

19. Hemimetabolous Orders
Blattodea
From Latin for “cockroach”
Broad body
Head tucked far under thorax
Wings (if present) lie flat, overlapping in abdomen

21. Dermaptera Derm--skin, -ptera--wings Chewing mouthparts
2 pairs wings, may be very short
Cerci at tip of abdomen
Feed mostly on dead vegetation
can attack green leaves and fruit, small insects
Found near carrion--probably eating maggots
Pincer bugs, earwigs

23. Isoptera Iso--equal, ptera--wings Termites Chewing mouthparts
Caste system--workers, soldiers, two or more types of reproductives
Workers very pale, soldiers have big heads
Primary reproductives--wings, eggs 2 yrs
Secondary reproductives within colony, wing pads, eggs per day

25. Hemiptera Hemi--half, -ptera--wings True bugs
Sucking mouthparts arising in front of middle of ventral surface of head
Hemelytra
Bedbugs, kissing bugs

27. Holometabolous Orders
Lepidoptera
Lepid-scaly, -ptera--wings
Larvae (caterpillars) have chewing mouthparts
Adults have siphoning
Pupae either naked or encased in silken cocoon