The article discusses some features of the biology and ecology of E. granulosus in the conditions of the plains of Dagestan. Our studies and experiments have made it possible to understand that eggs of E. granulosus, which are under water, can maintain their infectivity on the level in 16-18 percent, 7-8 percent and 0 % after 6 months, a 1 year and 1,5 years, respectively. The survival rate of E. granulosus eggs after being under the plant substrate after 6 months was from 28 to 30 percent, after 1 year it was from 15 to 16 percent, after 1,5 years it decreased from 2 to 4 percent. The all eggs died after two years. Under the sun, the eggs also retain their invasiveness. It is equal to 2 to 4 percent after 3 months. And after 6 months, it can be equal to 0. Prepatent period of E. granulosus in puppies in the summer is from 80 to 90 days. This time is enough for the animal to become infected and helminths capable of laying eggs develop in its organs. Between 20 and 44 adults of E. granulosus have been found in the intestines of adult dogs (20, 31, 38 and 44). This is 37.5 %, 28.0 %, 29.7 %, 27.9 % less than the puppies. Research was also carried out in winter. The autopsy to detect 15, 26, 30, 37 specimens of adults of the hydatid worm (E. granulosus) in the intestines of puppies. This experience allows us to conclude that in the winter season, the prepatent period of E. granulosus increases by 6-9 days. The number of helminths decreases from 54.5 to 39.6 %.