[Effect of cattle color, age, size and behavior on the intensity of the attack and sucking attachment by gadflies].

Mechanisms of effect of some morphophysiological parameters of cattle (age, colour, weight, skin area, intensity of defensive movements) on the attacking and attaching activity of tabanid flies were studied. Investigations were carried out in the south of Pskov Province in small herds by the method of simultaneous recording of attacking and attaching tabanids on all animals of the herd. It was established that differences in the attaching activity of Haematopota, Tabanus and Hybomitra flies depend mainly on the parameters affecting the efficiency of their attacks and connected with the age of animals, intensity of defensive movements and the host's skin area. The former correlates with the age of cows negatively while the latter positively. Therefore, more tabanids attach themselves to old animals than to young ones. For Chysops flies the main factor determining their intensity of attachment is the intensity of attacking. When attacking the Chrysops flies show preference to animals of dark colour independent of their age. It is shown that the increase in the attacking intensity results in the decrease of its efficiency and therefore reduces the probability of attachment for each individual.