Hormonal regulation of metamorphosis.

1. The Corpus cardiacum secretes prothoracicotropic hormone.

2. PTTH stimulates the prothoracic gland to produce ecdysone.

3. Ecdysone is released periodically during molting (ecdysis) of the larva.

4. The Corpus allatum secretes juvenile hormone. High levels of JH signal leads to another larval stage, while low levels of JH promotes the formation of a pupa and metamorphosis.