Pre-genital appendages:

• Appendages prior to eight segments.
• It consists of the following:

I) Styliform appendages:

• In primitive apterygotes or in non-insect hexapods, there are pairs of small, unjointed styli each inserted on a basal sclerite called coxa along with eversible vesicles.

II) Collembolan appendages:

• On the third abdominal segments , a median love called ventral tube projects and at its tip long and tubular reversible vesicles are present in pair.

III) Cornicles or siphunculi:

• Paired secretory structures located dorsally on the abdomen of aphids.
• The cornicles produce substances that repel predators or elicit care giving behavior by symbiotic ants.

IV) Gills:

• Respiratory organs found in the nymphs (naiads) of certain aquatic insects.
• In Ephemeroptera (mayflies), paired gills are located along the sides of each abdominal segment
• In Odonata (damselflies), the gills are attached to the end of the abdomen.
• The gills have direct role in gaseous exchange and more importantly to maintain a flow of water over the body.

V)Prolegs or pseudolegs:

• Except to the three pairs of thoracic legs, leg like outgrowths of the body wall in abdominal region are the feature of many holometabolous insects and are called prolegs or pseudolegs or non-thoracic legs or temporary legs.
• They are fleshy, locomotory appendages found only in the larvae of certain orders (notably Lepidoptera, but also Mecoptera and some Hymenoptera).

Based on number of prolegs the larvae are categorized to following types:

1) caterpillar: Larvae with 5 pairs of prolegs one pair each on 3-6 and 10 segments, example: cabbage butterfly larvae

2) Pseudo caterpillar: The larvae with 6-9 pairs of legs one pair each on 2 to 7th and 10th segments, example: sawfly

3) Loopers: Only two pairs one pair each on 6th and 10th segments, example: inch worm larvae.

4) Semiloopers: The larvae have three pairs of prolegs, example: cabbage semi-loopers