| Ametabolous (No metamorphosis) | Newly hatched creature looks exactly like an adult except for size and development of spine and setae. e.g. Silverfish and Spring Tails. |
Hemimetabolous (Incomplete metamorphosis) | Immature stages are the nymphs which are aquatic and respire by tracheal gills. Adults are terrestrial or aerial and respire by tracheae. e.g. Mayflies, Dragonflies, Stone-flies. |
| Paurometabolous (Gradual metamorphosis) | Newly hatched creature resembles an adult in general body form, but lacks wings and external genital appendages. Undergoes several nymphal stages through successive moult to becomes adult. e.g. Grasshoppers, Aphids, Stink bug. |
| Holometabolous (Complete metamorphosis) | 4 developmental stages: egg, larva, pupa, adult |
Hormonal Control of metamorphosis in insects:
-Brain Hormone
Secreted from neuro-secretory regions of the brain.
Chemically, it is a lipid.
Activates Corpora cardiaca – component of retrocerebral complex of the stomatogastric nervous system.
-Prothoracicotropic Hormone
Secreted by Corpora cardiaca.
Stimulates Prothoracic glands.
-Prothoracic Gland Hormone
Secreted by Prothoracic gland.
Chemically Ecdysone — triggers moulting as it acts on the tissues to promote all of the changes characterising a moult.
-Juvenile Hormone
Secreted by Corpora allata, another component of the retrocerebral complex.
Promotes metamorphosis.