[2] Between 1908 and 1927, Kopeć published at least 17 papers, in Polish, English and German, on insect endocrinology in various professional journals.
[2] Kopeć began his studies of the moulting of insects with Lymantria dispar[3] from specimens caught in the wild.
[4] His subsequent scientific activities helped determine the role of the insect brain in hormone production.
He was the earliest researcher to understand the importance of the insect brain, as is demonstrated by his statement in a 1917 paper: "For the normal process of metamorphosis the presence of the brain, at least up to a certain moment, is indispensable..."[2] Kopeć's most significant contribution was his study of neurosecretory cells in the brains of insects which secrete a crucial growth hormone, prothoracicotropic hormone (PTTH), which regulates the process of metamorphosis (ecdysteroidogenesis).
[7][8] Kopeć's work was cut short due to his arrest by the Gestapo in 1940 together with his daughter Maria and son Stanisław in an operation against a Polish Underground State-run secret university.