Larva and it’s Types

Larva

• It has been defined as an intermediate stage in the life history of Invertebrates and few lower chordates.
• In class Insecta, larva signifies the reproductively immature stage which is determined for feeding and gathering energy for transformation into adult.
• Class Insecta is a diverse category among the animal kingdom. Many of them vary in their mode of life especially in feeding.
• Depending over this we have four categories of larvae –
  • Protopod
  • Apod
  • Oligopod
  • Polypod

‌PROTOPOD LARVA

• A precocious larva showing few segmentation and lacks cephalic or thoracic appendages i.e. compound eyes, antennae, legs.
• These are parasitic to other insects and lives in haemocoel, as it serves the suitable environment for survival.
• Example- larvae of genus Platygaster.

APOD LARVAE

• Larvae provided with defined head but lacks true thoracic appendages, are termed as apod larvae.
• They are also termed as vermiform owing to worm like appearance.
• Apod larvae characteristically belongs to order Hymenoptera and Diptera.
• Apod larvae further categories as follows-
  • Eucephalous
  • Hemicephalous
  • Acephalous

EUCEPHALOUS LARVAE

• They have well sclerotized head capsule along with reduced cephalic appendages.
• Example- Vespa orientalis (Red wasp)

HEMICEPHALOUS LARVAE

• Head capsule and cephalic appendages are reduced and could be drawn back into thorax.
• Example- Tabanus (Horse fly), Robber fly, Apis (Honeybee).

ACEPHALOUS LARVA

• Sclerotized  head is absent.
• Cephalic appendages may be drawn in thorax.
• Example- larva of House Fly: MAGGOT (Acephalous larva of House fly is known as maggot).

OLIGOPOD LARVAE

• Larvae provided with true thoracic legs and sclerotized head fall in this group.
• These are further graded as:
  • Scarabaeiform
  • Campodeiform
  • Elateriform
  • Platyform

SCARABAEIFORM LARVAE– These are C-shape curled larvae and also termed as Grub. Example- Larvae of order Coleoptera.

CAMPODEIFORM LARVAE– Campodeiform itself defines the elongated, dorso-ventrally flattened body. These larvae have prognathus head, long thoracic appendages and abdominal cerci or caudal processes. Example- They are active predators found on order Trichoptera and Neuroptera. They resembles to the genus Compodea of order Diplura thus named so.

Carabiform larvae– These are Campodeiform larvae that have thoracic appendages and abdominal cerci.

PLATYFORM LARVAE- Also termed as Onisciform larvae. Identified by broad and flattened body. Example- larvae of Bat flies.

POLYPOD LARVAE

• Also termed Eruciform larvae. In addition to thoracic legs larva has stumpy prolegs( cleates suction grip over the surface) on abdominal segments.
• Based upon presence of prolegs POLYPOD larvae categories as:
  • Caterpillar
  • Semilooper
  • Looper

CATERPILLAR – Polypod larva having 5pairs of prolegs on 3rd, 4th, 5th, 6th and 10th abdominal segments. Example- Characteristically the larvae of order Lepidoptera.

SEMILOOPER – Polypod larva having 3 pairs of prolegs on 5th, 6th and 10th abdominal segments and form semi loop while moving. Example- Thysanoplusia orichalcea.

LOOPER – Polypod larva having 2 pairs of prolegs on 6th and 10th abdominal segments and forms complete loop while moving.