EN
1. In the course of a survey of cattle undertaken in the Poznań province in April 1966, 7568 head of cattle were examined in 74 farms. The work has been done in close co-operation with the local veterinary authorities. The following species of lice, hoth sucking and biting, were found in the investigated area: Damalinia bovis L., Hacmatopinus eurysternus Nitzsch, Linognathus vituli L. and Solenopotes capillatus End., the long-nosed cattle louse L. vituti not having been reported in Poland so far. 2. Cases of mixed infestation with 2 or more Phthiraptera species occur in the investigated province. 3. The incidence of lice was of 15 per cent, and another 28,1 per cent of cattle lived in lice-infested cow-sheds. It means that some 43 per cent of the cattle were heavily exposed to infestation. 4. The number of lice estimated by the Matthysse method seemed to be low (symptomless infestation) in some 40% of infested cattle, it was moderate (i.e. accompanied by loss of hair and desquamation) in 48 per cent of the cattle, and heavy in another 10,8 per cent of infested cattle (the skin seriously affected). 5. Infested cattle was found to live in about 60 per cent of the examined cow-sheds. 6. To estimate the viability of eggs found on cattle, 33 samples of 50 eggs each were tested in a period shortly before the rapid spring decrease of the louse population. From the results obtained one might conclude that the decrease just mentioned depends very little on the viability of lice eggs.