Prothoracicotropic hormone
Prothoracicotropic hormone (PTTH) was the first insect hormone to be discovered. It was originally described simply as "brain hormone" by early workers such as Stefan Kopeć (1922) and Vincent Wigglesworth (1934), who realized that ligation of the head of immature insects could prevent molting or pupation of the body region excluded from the head if the ligation was performed before a critical age in the lifestage was reached. After a certain point the ligation had no effect and both sections of the insect would molt or pupate. However, implantation of a conspecific brain to a sessile ligated abdomen or an abdomen under diapause would induce molting or pupation. Thus, the brain was originally thought to be the source of the hormone that induces molting in insects.
Epiandrosterone
Epiandrosterone, or isoandrosterone, also known as 3β-androsterone, 3β-hydroxy-5α-androstan-17-one, or 5α-androstan-3β-ol-17-one, is a steroid hormone with weak androgenic activity. It is a metabolite of testosterone and dihydrotestosterone (DHT). It was first isolated in 1931, by Adolf Friedrich Johann Butenandt and Kurt Tscherning. They distilled over 17,000 litres of male urine, from which they got 50 milligrams of crystalline androsterone (most likely mixed isomers), which was sufficient to find that the chemical formula was very similar to estrone.