Educated at Belvedere College, and subsequently at University College Dublin, he graduated from University College Dublin both as a medical doctor and with a Masters in Science. He subsequently earned a PhD in Zoology. O’Rourke’s 1948’s survey of Irish ants built on the earlier work of Stelfox and provided an authoritative description of Irish ants. O’Rourke (1956) provided an early consideration of the importance of ants as disease vectors. He was appointed Professor of Zoology at University College Cork and was elected a Member of the Royal Irish Academy and Fellow of the Royal Entomological Society of London.