POUR-ON SYSTEMIC INSECTICIDES FOR THE PROTECTION OF CALVES FROM LINOGNATHUS VITULI

In this study early winter treatments with Ruelene, Co-Ral, Famphur, and Korlan prevented the development of high infestations of the long-nosed sucking louse, Linognathus vituli (L.), on range-reared, 8- to 11-month-old, Hereford calves. Each test group consisted of a segregated subgroup of steers and a similar subgroup of heifers. Infestations were assessed by a point-score method based on examination of three areas of the body. One hundred days after all treatments the infestations were significantly lower than at the time of treatment. Infestations on steers and heifers were not significantly different. Low infestations were uniformly distributed over the three examination areas, but as infestations increased on the untreated check groups, the highest infestations developed on the heads.