The effect of herbicidal killing of shrubs on the numbers of host-seeking adult Dermacentor andersoni Stiles studied at 4 sites near Kamloops, British Columbia, from 1965 to 1972. After preliminary herbicide tests, selected plots were sprayed with a mixture of 2,4-D and picloram in 1966, with follow-up treatments of picloram pellets in 1967 and 1968. Adequate kills of Amelanchier, Rosa , and Prunus spp. were obtained after the 1st treatment at 3 of the sites. After the relatively resistant Symphoricarpos and Clematis were killed by the pellets, areas concerned were invaded by Bromus tectorum . Annual sampling of ticks by ‘flagging’ showed no consistent and significant differences in numbers on treated and untreated transects.