External morphology

Question 1

Head

Answer 1

Mouthparts + eyes + antennae

Question 2

Mouth parts

Answer 2

Mandibulate: Adapted to chewing
* Clypeus: Where labrum is attached
* Labrum: “upper lip”
* Mandible: grasp, cut, & chew
* Maxilla: food manipulation
* Maxillary palps: sensory structures
* Labium: “Lower lip”
* Labial palps: Attached to labium

Haustillate: Derived from mandibulate for liquid diet
* Piercing-sucking: True bugs
* Chewing-lapping: Bees/wasps
* Siphoning (or sucking):
* Sponging: Non-biting flies
* Cutting sponging: Biting flies

Question 3

Orientation of head/mouthparts

Answer 3

• Hypognathous: Ventrally
• Prognathous: Anteriorly
• Opisthognatous: Posteriorly

Question 4

Antennae

Answer 4

• Antennal socket
• Scape: First segment
• Pedicel: 2nd segment
• Flagellum: Most variable part. Made of flagellomeres

Question 5

Eyes

Answer 5

Compound eyes
* Main visual organ in insects
* Made of multiple ommatidia

Simple eyes:
* No image, detects light intensity
* Not all insects have

Question 6

Thorax segments

Answer 6

Divided into 3 segments:
* Prothorax
* Mesothorax
* Metathorax

Question 7

Size of thorax segments

Answer 7

• Same size in primitive wingless & immature insects
• Mesothorax & metathorax enlarged in winged insects for extra flight muscles

Question 8

Thoracic segment regions

Answer 8

• Notum: dorsal region
• Sternum: Ventral region
• Pleuron: Lateral region

Question 9

Legs structure

Answer 9

• Coxa
• Trochanter
• Femer
• Tibia
• Tarsi: Last segment = claws with various pad-like or bristle-like structures.

Question 10

Legs Function

Answer 10

Typically adapted for walking (ambulatory) and running (cursorial). May be modified for:
* Jumping = saltatorial
* Grasping = raptorial
* Digging = fossorial
* Swimming = natatorial

Question 11

Wings

Answer 11

• Fully functional wings are found only in adult stage (except mayflies).
• Most have 2 pairs of wings

Question 12

Wings modifications

Answer 12

Tegmina:
* Thicker & leathery
* Praying mantis, cockroaches, earwigs, grasshoppers

Elytra:
* Heavily sclerotized
* Found in beetles.

Hemelytra
* Thickened basal section and membranous apical section
* Heteroptera

Question 13

Wing veins

Answer 13

• Sclerotized
• Longitudinal and cross-veins

Question 14

Abdominal segments 1-7

Answer 14

Pregenital segments
* Usually without appendages

Few exceptions: silverfish (styles) & immature insects (prolegs, gills)

Question 14

Abdomen function

Answer 14

Contains organs of reproduction, digestion, excretion, respiration

Question 14

Primitive vs modern insects segments

Answer 14

• Primitive: 11
• Modern: no more than 10

Question 15

Abdominal segments 8-11

Answer 15

Non reproductive and reproductive appendages

Non reproductive:
* Cerci (sing. Cercus): Paired appendages at posterior end of abdomen
* Normally sensory organs, sometimes modified into defensive organ

Reproductive appendages:
* Associated with copulation and oviposition
* Ovipositor: Used for egg-laying, may be modified for piercing/sawing

Question 16

Abdominal regions

Answer 16

• Tergum: dorsal region of an abdominal segment
• Tergite: Hard plate of the tergum
• Sternum: ventral region of an abdominal segment
• Sternites: Hard plate of sternum