EN
One problem underestimated by veterinarians and farmers in horses is diptera Hippobosca equina, a blood-sucking insect that annoys horses and causes skin injuries. The aim of the presented studies was to estimate the extensiveness and intensity of Hippobosca equina invasion in primitive Polish horses during the grazing period. Studies were carried out from July to October on 15 mares, 10 sucking foals, as well as on 15 young stallions and 13 young mares. Insects were counted in all animals once in mid June, then daily from July 24 to 29, next on August 16, September 20 and October 25. In July the presence of Hippobosca equina was not found in mares and sucking foals, but in young horses the invasion occurred in more than 53% of stallions and about 76% of mares. Daily examinations in July showed the presence of diptera in all groups, but not in all animals. The maximum invasion extensiveness in mares (80%) occurred July 28, while in foals July 26 (90%) and August 16 (70%). In 1.5-year-old mares and stallions H. equina occurred in July and lasted up to September. The greatest number of insects (up to 11) was found July 29 in one stallion and July 25, 27 and 29 in mares (up to 29). The extensiveness of invasion in young stallions in the early part of the summer fluctuated between 53.3% (June) and 93.3% (July 27) and decreased in September to about 27%, while in young mares it was more than 92% in July and August and 30.8% in September. Hippobosca. equina did not occur in October in 1.5-year-old horses.