On 5 June 1972 he received the scientific title of Candidate of Biological Sciences based on his thesis "Defense reactions and premature pathogenic extinction of woody plants".
[1] Jiří Paclt was married to his wife Vera, né Vaněčková (*1920, Prague – †2006, Bratislava), with whom he had three children: the daughters Helena (a high school teacher) and Eva (an economist), and the son Roman (an engineer and programmer).
In the following years until 1962, he was a researcher at the Institute of Biology of the Slovak Academy of Sciences in Bratislava, where he first worked in the Faunistic Laboratory, and later in the Zoology Department.
He spent almost 30 years of his work life, from 1962 to 1990, at the Institute of Experimental Phytopathology and Entomology in Ivanka pri Dunaji, from where he eventually retired.
[1] Both his diploma and doctoral thesis focused on botanical topics, and Paclt continued with research in botany throughout his work life.
His main groups of interest were springtails, proturans, diplurans, jumping bristletails, silverfish, butterflies and moths, beetles and mayflies, of which he studied the morphology, taxonomy, systematics, ecology and zoogeography.