Studies of the attack activities, displacement and persistence time in the search for blood repast of several species of tabanids, are being developed in open areas of pasture located on the Goeldi Museum's Research Campus, Belém, Pará and on the Morelândia farm, municipality of Santa Bárbara, Pará. The objectives are: to define the capacity of displacement of these insects in search of blood repast; to analyze the influence of wind, locally, in the displacement of tabanids, and analyze the time (in hours and days) that each species resumes the search for repast. To define the displacement capacity, 3 horses were used as bait, 10, 30, 50, 70 and 110m away from two points defined for release. To analyze the influence of wind, 4 horses placed 30m from a release point were used. To determine the time to return to the tabanids' roost, only one horse was used as bait. The tabanids were marked with non-toxic ink and then released at the determined points. The recapture results show that the species with the highest capacity to move were: Tabanus occidentalis (19.2% at 10m, 8.2% at 30m, 11.1% at 50m, 10.6% at 70m, 4.7% at 90m, and 2.0% at 110m), T. trivittatus (6.3% at 10m, 3.6% at 30m, 1.3% at 50m, 2.0% at 70m, 0.4% at 90m and 0.4% at 110m) and T. sorbillans (12.1% at 10m, 3.3% at 30m, 4.3% at 50m, 8.3% at 70m). As for wind influence, large variations in wind direction were observed during the day and locally there was no influence. The species that persisted the longest to resume foraging were: T. occidentalis (42.4%), T. discus (31.5%) and T. trivittatus (8.0%). Statistical tests of linear correlation, binomial and adherence were applied. These results present new and useful information for livestock management, suggesting that a distance of 200 m between herds is sufficient as a barrier to prevent attack of tabanids among their hosts.
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