Entomology Exam Notes

Neuroptera

  • Includes lace wing bugs/Aphidlions.
  • Small to medium sized, attractively colored.
  • Wings are placed in a roof-like manner on the abdomen.
  • Show complete metamorphosis.
  • Larval stage: Campodeiform type.
  • Pupal type: Exarate (generally).
Types of Larvae:
  1. Eruciform: Features thoracic legs along with abdominal legs.
  2. Scarabaeiform: C-shaped larvae.
    • Mouth part: Mandibulo-suctorial type
  3. Campodeiform: Only thoracic legs.
Pupal Types:
  1. Obtect type: Appendages are not free.
  2. Exarate Type: Seen in beetles. Appendages are free.
  3. Coarctate Type: Pupa is covered with the last larval skin (puparium).

Thysanoptera

  • Fringed wings are present.
  • Minute insects.
  • Moniliform antennae (string of beads).
  • Sense cones/sensoria on the 3rd and 4th segments.
  • Compound eyes are conspicuous.
  • Mouthparts: Asymmetrical, rasping and sucking type.
    • Left mandible is absent.
    • 3 stylets are present.
  • Legs have a bladder called pretarsus vesicles.
  • Cercus absent.
  • Abdomen: 10-11 segmented.
  • There is an inactive pupal instar stage in metamorphosis known as pseudo pupa.
Suborders:
  1. Terebrantia: Female with appendicular ovipositor; wing venation is present.
  2. Tubulifera: Ovipositor is absent; abdomen is tubular; wing venation is absent.

Isoptera (Iso: Same, Ptera: Wings)

  • Social Insects, e.g., Termites
  • Castes:
    • Reproductive: Queen, Male
    • Non-Reproductive: Workers, Soldiers
  • Genetically controlled.
  • Tarsus: 4 segmented
  • Cercus is short and segmented.
  • Pronotum: Saddle-shaped.
  • RsR_s (Radius Sector vein) is absent
  • Colonies: Termitaria / Mounds
  • Wing shedding occurs after the swarming process, along the basal/humeral suture.
    • Remaining body after wing shedding: Stub.
  • Alate form (winged form): Compound eyes are present.
  • Apterous form (wingless form): Compound eyes are absent.
  • Trophallaxis: Exchange of food between termites.
  • Physogastry: Queen termites attain enormous size after mating.

Odonata (Odonto = tooth)

  • e.g., Dragonfly, Damsel fly.
  • Zygoptera & Anisoptera
  • Holoptic eyes.
  • Mouthparts: Mandibulate
  • Male genitalia: Located on the 2nd & 3rd abdominal segments.
  • Both fore and hind wings are membranous.
  • They can't fold their wings.
  • Labium is called Mask.
  • Nymph stage is aquatic.
  • Nymph is called as Naiad.
  • Leg: Scooping type: forms a basket-like structure.
  • Wheel position - during mating in Abdomen.
  • [Sperms] Gonopore are produced in Abdominal Segment
  • Attractively colored.
  • Functional Gonopore is present in 9th Abdominal Segment.
  • Maxillae consists of Galea and Lacinia, that fuse to form mala.

Blattidae (of Dictyoptera)

  • Hypognathous head.
  • Mouthparts: Mandibulate.
  • Filiform antennae are present.
  • Forewings are called Tegmina.
  • Tarsus: 5 segmented.
  • Cerci sensory organs are present.
  • Stridulatory organs are absent.
  • Eggs are laid in ootheca.
  • e.g: Cockroach

Dictyoptera (Dictyo: Net, Ptera = wing)

  • e.g., Cockroach, Preying Mantis
  • Hypognathous type of head.
  • Mouthparts are Mandibulate.
  • Filiform antennae are present.
  • Wings: forewings are called tegmina.
  • Anal lobe is present in Hind wing.
  • Tarsus: 5 segmented.
  • Cerci: long and elongated- multi segmented.
  • Incomplete metamorphosis.
  • Eggs are held in ootheca.
  • Walking legs are called Ambulatorial.
  • Running legs are called Cursorial!

Mantidae

  • e.g., Preying Mantis (Mantis religiosa)
  • Prothorax is elongated; Meso and Meta thorax are fused with the abdomen.
  • Legs: modified for capturing prey (Raptorial legs).
  • Cryptic Coloration is present.
  • Eggs are laid in Spumaline (egg case).

Acrididae (short horned Grasshopper)

  1. Antennae filiform are shorter than the body with less than 30 Segments.
  2. Pronotum is shield-like.
  3. Auditory organs on either side of 1st abdominal segment.
  4. Stridulation: Femoro-alary Type
  5. Tarsus: 3 Segmented.
  6. Hind legs are modified for jumping.
  7. Ovipositor short and well developed.
  • Plant feeders and are often very destructive
  • e.g: Rice Grasshopper, Cotton Grasshopper, Calotropis Grasshopper

Tettigonidae (Long horned Grasshopper and Katydid)

  1. Cryptic coloration.
  2. Tarsus = 4 segmented.
  3. Stridulation: Alary Type.
  4. e.g: Surface Grasshopper.

Auditory Organ

  • Auditory Tympanal organs are well developed and are located on either side of the abdominal segmentation or at the base of fore tibias

Stridulation (Producing sound)

  • Usually males can produce sound.
  • 2 types of Stridulation: Alary type and Femoro-alary type
    • Alary type = Ensifera
    • Femoro-alary type = Short, horned/caelifera
Alary type:
  • At the base of one forewing along a file-like ridge on the ventral side of the other forewing.
  • Both the forewings have a file and scraper.
  • The file is longer in the upper wing and the scraper is well developed in the lower wing.
  • Sound is produced by rubbing a sharp edge called Scraper
  • Forewings are vibrated at about 450 when sound is produced
Femoro alary Type:
  • The femur of hind legs is rubbed with tegmina.

Orthoptera

  • Ortho: Straight, Ptera: Wings.
  • e.g., Grasshopper, Locust, Cricket
  • Medium-large sized insects with elongated body.
  • Hypognathous / prognathous type of head.
  • Filiform antennae
    • Long: Ensifera
    • Short: Caelifera.
  • Chewing and biting type of mouthparts.
  • Forewings are leathery and tough (Tegmina).
  • Membranous hind wings are present.
  • Females with well-developed ovipositor.
  • Forewings of Grasshopper: Tegmina
  • Prothorax large and its notum extends laterally to conceal or cover propleuron
  • Hind legs are modified for jumping (Saltatorial).
  • Tarsus 3-4 Segmented.
Legs:
  • 6 Segments of leg of insect: Coxa, Trochanter, Femur, Tibia, Tarsus, Pre-Tarsus.