Insect Anatomy and Wing Types

Insect Wings

• Elytra: Hardened front wings that protect membranous hindwings, found in beetles (Coleoptera)
• Hemelytra: Leathery wings at the base and membranous at the tip, characteristic of true bugs (Hemiptera)
• Tegmina: Completely leathery or parchment-like front wings, present in grasshoppers and mantises (Orthoptera)
• Haltere: Small, knob-like structures serving as gyroscopic organs for balance, found in flies (Diptera)
• Fringed Wings: Slender front and hindwings with long fringes of hair, typical of thrips (Thysanoptera)
• Membranous wings: Soft, flexible, transparent wings with prominent veins, present in bees, dragonflies, and damselflies (Hymenoptera, Odonata)
• Membranous wings with scales: Wings covered with powder-like scales, found in butterflies and moths (Lepidoptera)

Insect Abdomen

• Simple, anterior segments lack appendages
• Typically 10-11 segments
• Terga: Dorsal abdominal segments
• Sterna: Ventral segments
• Can expand for food storage and egg production

Abdomen Structures

• Spiracles: External openings of the trachea (respiratory tube)
• Tympanum: Hearing organ in insects

Abdomen Appendages

• Cerci: Sensory organs used in defense, propulsion, and copulation
• Cornicles: Found in aphids, secrete alarm pheromones
• Styli: Help to hold females during copulation
• Aedeagus: Penis of insects, male copulatory organ
• Ovipositor: Egg-laying apparatus of female insects, needle or blade-like
• Bursa Copulatrix: Reproductive organ of females
• Claspers: Used to hold the mate during copulation

Insect Thorax

• Responsible for locomotion (walking and flight)
• Composed of three segments:
  • Prothorax: Bears the first pair of legs (prothoracic legs)
  • Mesothorax: Bears a pair of legs and the first pair of wings (forewings)
  • Metathorax: Bears a pair of legs and the second pair of wings (hindwings)
• Pterothorax: Fused mesothorax and metathorax

Thorax Structures

• Spiracle: Breathing organ
• Tympanum: Hearing organ

Thorax Appendages

• Legs:
  • Coxa: Articulates with the thorax
  • Trochanter: Freely movable segment connecting coxa and femur
  • Femur: Largest and strongest segment, often modified for special functions
  • Tibia: Long and slender, aids in locomotion and may bear spines
  • Tarsus: Divided into tarsomeres (max 5), provides grip
  • Pretarsus: Claw-like segments, aid in climbing and holding

Types of Insect Legs

• Ambulatory/Gressorial: Walking legs with normal segments
• Cursorial: Running legs with well-developed coxa
• Saltatorial: Jumping legs with enlarged femurs and elongated tibia
• Fossorial: Digging or burrowing legs with broad, flat, and dense coxa and femur
• Raptorial: Grasping legs with long coxa, enlarged femur, and spines
• Natatorial: Swimming legs with flattened femur and tibia, tarsi fringed with hairs
• Scansorial: Clinging legs with modified tarsi for holding
• Corbiculate: Foraging or pollen-gathering legs with a depressed area (pollen basket) and fringed hairs

Wings

• Organ of flight, also used for protection and balancing
• Veins:
  • C: Costa
  • Sc: Subcosta
  • R: Radius
  • Cu: Cubitus
  • A: Anal
  • J: Jugal

Types of Insect Wings

• Plumose: Segments with whorls of long hairs
• Lamellate: Nestled plates
• Aristate: Last segment enlarged with a bristle
• Stylate: Last segment bearing an elongated terminal finger-like process