Tehran University of Medical Sciences Journal of Arthropod-Borne Diseases 2322-1984 6 2 2015 10 14 129 135 EN Nasrollah Vahedi-Noori Department of Parasitology, Faculty of Specialized Veterinary Sciences, Science and Research Branch, Islamic Azad University (IAU), Tehran, Iran Sadegh Rahbari Department of Parasitology, Faculty of Veterinary Science and Research Branch, Islamic Azad Univer- sity, Tehran, Iran Saeed Bokaei Department of Food Hygiene, Faculty of veterinary Medicine, University of Tehran, Tehran- Iran 2015 10 14 2015 10 14 Background: The present study aimed to demonstrate the seasonal activities of Ixodes ricinus at the pasture level and on the host. Methods: A vast pasture in Amol countryside (Mazandaran Province, Iran) which had the potential for a considera- ble number of cattle and sheep to graze was chosen. Tick sampling from the skin of 130 cattle and 130 sheep were collected every month interval. Simultaneously, the activity of the different stages of I. ricinus on the pasture was considered by dragging method. The collected ticks were placed in jars containing 70% alcohol and sent to the para- sitological laboratory for identification. Results: The rate of the infestation with adult I. ricinus in cattle and sheep increases gradually with the beginning of fall and reaches its peak in January, February and March while it starts to decline with the beginning of spring as the infestation rate reach to zero in summer months. Accordingly, the highest number of adult I. ricinus existed on the cattle during January, February, and March. In addition, the results of dragging have been revealed that the active tick population in the pasture exists during November, December, January, and March. Conclusion: Ixodes ricinus is regarded a common tick species in  Amol (Mazandaran). Due to the biological properties of I. ricinus which is active in the cold and humid months of the year, the prevalence of ruminant infestations with I. ricinus in this area increases from November to March but reaches to zero again with the beginning of summer. https://jad.tums.ac.ir/index.php/jad/article/view/167 https://jad.tums.ac.ir/index.php/jad/article/download/167/151