The study of the Chirpan Eminences tabanid fauna was completed by means of a route collection in 2008 and regular monthly collections from two localities during the active tabanid seasons in years 2010-2011. The research resulted in the capturing of 1202 tabanid specimens, 1124 of them were females and 78 males. Within this collected sample 24 species and subspecies from 8 genera were determined: Chrysops (2 species), Atylotus (1 species), Therioplectes (1 species and 1 subspecies), Hybomitra (3 species), Tabanus (12 species and 1 subspecies), Haematopota (1 species), Dasyrhamphis (1 species) and Philipomyia (1 species). On the basis of literary data and of the species identified in this research, it may be asserted that the tabanid fauna in the Chirpan Eminences is represented by 28 species. Thirteen of them were identified for the first time for this region. From a zoogeographical point of view, predominant for the tabanid fauna of the Chirpan Eminences are the elements of the Mediterranean subregional fauna (64.29 % of the species).

The aim of the present study was to explore the seasonal activity of tabanids on the territory of the Chirpan Eminences, in Stara Zagora region, Bulgaria. The study was carried out during the flight period (May - September, 2010 - 2011). A total of 1034 specimens of tabanids from 23 species and 8 genera were collected and identified. The horse flies began flying during the second half of May and its flight period lasted until mid - September. The peak of seasonal abundance was observed during the first half of July. The most abundant species in the horse flies assemblages on the Chirpan Eminences were Tabanus quatuоrnotatus (35.30%), Tabanus tergestinus (28.05%) and Philipomyia graeca (10.93%). The largest number of specimens of T. tergestinus was collected during the peak of seasonal abundance of horse flies on the territory of the Chirpan Eminences.

A study was conducted on the dynamics of tabanids daily activity in the Central Balkan Mountains in the 2011-2013 period. Tabanids have been found to fly 11 hours a day, with a peak in activity around 11:00. Their mass activation is in the temperature range 18-23°С and at 26°С maximum activity has been reported. In the present study a new, minimum temperature threshold for activation of T. quatuornоtatus Mg. in Bulgaria was registered (13°С).

The seasonal activity of the tabanids (Diptera: Tabanidae) was studied from May to September (2010-2011) in three localities on the territory of the Central Balkan Mountains. A total of 2232 specimens from 25 tabanid species and 8 genera were collected and processed. The first horse flies emerge in the first half of May and the last specimens were collected until mid-September. The tabanids reached their highest peak abundance in the first half of July. The most abundant species of the tabanid assemblages in the Central Balkan Mountains were Tabanus tergestinus Egg. (56.73 %), Tabanus bromius L. (12.71 %) and Haematopota pluvialis L. (8.87 %). The largest number of specimens of T. tergestinus was collected during the peak of the seasonal abundance of horse flies on the territory of the Central Balkan Mountains.

The study was conducted in the Central Balkan Mountains in the 2010-2013 periods. On the basis of new and literature data it was summarized that the tabanid fauna in the region is represented by 41 species of 10 genera. The species Tabanus leleani Austen, 1920 is reported for the first time for the fauna of Bulgaria. The phenological features of 31 species of tabanids registered during the study in the region have been analyzed. The terms of activity of the most common tabanid species have been confirmed. The flight period of Tabanus sudeticus Zeller, 1842 in Bulgaria (from the middle of June to the middle of August) are marked.