The duration of rest and feeding greatly affects the re-breeding of ectoparasites: Hirudo verbana, Hirudo medicinalis and Hirudo orientalis.

Ectoparasitic leeches have many biologically active substances in their body, which are able to show various therapeutic effects, which makes them very relevant in the study. Among them, the most common are medicinal leeches: Hirudo verbana, Hirudo medicinalis and Hirudo orientalis. They are listed in the Red Book as a vulnerable species, so their population is mostly supported in biolabs. Therefore, the search for different methods of their preservation is relevant. The aim of the work was to test the effect of the duration of rest and feeding of animals for re- reproduction, which will increase their population. For the study, three experimental animal groups were formed: 1 control - the animals were fed a week after the first reproduction, re-reproduction occurred not earlier than 2 months; 2 experimental - selected animals that remained clitellum after the first reproduction and again sent to the peat-soil environment for reproduction without rest and feeding; 3 experimental - selected animals that remained clitellum after the first reproduction, fed after 1 week, after another 1-2 weeks again sent to the peat-soil medium for reproduction. As a result of the study, the restoration of the physiological state after the first dilution in the first and third groups was registered. In the second group, the animals are depleted as a result of defective offspring, mortality of them and their offspring.