Subphylum: Hexapoda

Subphylum: Hexapoda

1. Insecta + 3 related wingless orders (Class Entognatha): Collembola, Protura & Diplura

2. About 1 Million species described (7000 new sps per year) → 400 000 beetles alone

3. 80% of World crop plants need pollinators → virtually all insects

4. Fundamentally terrestrial, but some groups have invaded aquatic environments secondarily (mainly freshwater)

5. Body subdivided into 3 well-distinct parts → head,thorax & abdomen

6. 3 pairs of thoracic legs; 1 pair of antennae; 3 sets of jaws (mandibles, maxillae & labium)

7. Aerial gas exchange system → tracheae + spiracles

8. Malpighian tubules → excretory organs

9. Wings → Pterygota only

10. Feeding & Mouth Parts

    • Mouth (bite-chewers)→ bordered anteriorly by clypeo- labrum, posteriorly by labium (with 2 palps), on sides by mandibles (no palps) & maxillae (with 1-7 articles palp); median tongue-like hypopharynx (salivary glands opening)

11. Development ►Simple development → young hatch out as juveniles very similar to adults (primitive wingless orders) ►Hemimetabolous development → series of gradual changes or incomplete metamorphosis (Orthoptera, Hemiptera, Odonata +) ►Holometabolous development → series of radical changes or complete metamorphosis (Lepidoptera, Coleoptera, Diptera +)

12. CLASSIFICATION

    • Class: Entognatha = base of mouthparts hidden within head capsule; small size (< 1 cm) → 3 orders: Collembola, Protura, Diplura
      • Order: Collembola = springtails (6000 sps, < 6 mm); appendages in 4th-5th abdominal segment forming furcula (springlike structure driven by hemocoelomic fluid pressure)
      • Order: Protura (205 sps, tiny < 2 mm); found in leaf litter, moist soils & rotting vegetation
      • Order: Diplura = bristetail (650 sps, < 4 mm); with caudal cerci (segmented filaments)
    • Class: Insecta → ectognathous = mouthparts exposed & projected from head capsule → 3 sub-classes, 30 orders
      • Sub-class: Archaeognatha
        • 1) Order: Archaeognatha → jumping bristetails (255 sps, < 15 mm); with 3 caudal filaments resembling silverfish but more cylindrical
      • Sub-class: Zygentoma ► 2) Order: Thysanura → silverfish (450 sps, < 30 mm); with 3 caudal filaments, body covered with scales
      • Sub-class: Pterygota (paired wings on thoracic segments 2 & 3)
        • 3) Order: Ephemeroptera 4) Order: Odonata Mayflies → fresh water Dragon & Damselflies (2100 sps) (5000 sps)
        • 5) Order: Plecoptera 6) Order: Blattodea Stoneflies → fresh water Cockroaches (1600 sps) (4000 sps)
        • 7) Order: Isoptera 8) Order: Mantodea Termites→ wings shed Praying mantis form large colonies (2000 sps) (1800 sps)
        • 9) Order: Grylloblattodea 10) Order: Dermaptera Rock crawlers→ 15-30 mm Earwigs in glaciers & ice caves with sclerotized forceps (25 sps) (1200 sps)
        • 11) Order: Orthoptera 12) Order: Phasmida Grasshoppers Stick & leaf insects stridulation (forewing - femur) up to 35 cm long (13000 sps) (2600 sps)
        • 13) Order: Mantophasmatodea 14) Order: Embioptera Gladiators → described in 2002 Web-spinners (10 mm) Namibia, South Africa in spun silken galleries & Tanzania (20 sps) (150 sps)
        • 15) Order: Zoraptera 16) Order: Psocoptera Termite-like (< 3mm long) Psocids - book & bark lice form colonies in dead wood tiny, 1-10 mm long (25 sps) (2600 sps)
        • 17) Order: Phthiraptera 18) Order: Thysanoptera Sucking & biting lice(< 5mm) Thrips ectoparasites of birds tiny, 0.5-1.5 mm long & mammals (5000 sps) (4100 sps)
        • 19) Order: Hemiptera 20) Order: Strepsiptera True bugs, cicadas, aphids Males free-living & winged & scale insects Females wingless & (85000 sps) parasitic on other insects (300 sps)
        • 21) Order: Megaloptera 22) Order: Raphidioptera Dobsonflies, alderflies etc Snakeflies (200 sps) (50 sps)
        • 23) Order: Neuroptera 24) Order: Coleoptera Ant lions & lacewings etc Beetles (4550 sps) (400000 sps)
        • 25) Order: Mecoptera 26) Order: Siphonaptera Snowflies, scorpionflies etc Fleas (550 sps) (2400 sps)
        • 27) Order: Diptera 28) Order: Trichoptera True flies, mosquitos etc Caddisflies (150000 sps) (7100 sps)
        • 29) Order: Lepidoptera 28) Order: Hymenoptera Butterflies & moths Bees, wasps, ants etc. (120000 sps) (125000 sps)