Abstract: | An experiment was carried out in South Bohemia, in which 10% water emulsion of diethyltoluamide was used as repellent against bloodsucking Diptera to protect pastured dairy cattle. The repellent was applied by means of a spraying frame and was effective for 30-36 hours. Seven mosquito species and 18 horsefly species were observed to be attacking the cattle. The average number being 120-300 mosquitoes and 50 horseflies per hour, the milking qualities in the cattle decreased by 6.2%, the milk fat content by 11.8%. After converting to milk with average fat content of 4%, the difference in milking qualities between treated and untreated animals was 9.7%. |