The efficacy of trunk treatment with three materials, cotton seed oil, lime and used motor oil, were evaluated for the control of apple clearwing, Synanthedon myopaeformis (Borkhausen) (Lepidoptera: Sesiidae) in an apple orchard during two successive years (2004 and 2005). The weekly total number of adult catches and exuviae was recorded each year. No treatments caused significant reductions in mean numbers of adults caught in bait traps or the exuviae protruding from the barks of tree trunks and thick branches in the first year of the study whereas all of them differed significantly from each other or from water-treated control in the second year (P < 0.05). A comparison of the mean numbers of adult catches and exuviae in both years revealed significant differences between the used motor oil and cotton seed oil treatments (P < 0.05). The lime treatments in both years significantly differed in terms of adult catches, but not exuviae (P<0.05). In the second year, compared with those in water-treated control plots, the mean number of adult catches and exuviae decreased by 81.3% and 88.3% in the used motor oil-treated plots, and by 70.8% and 83.3% in the cotton seed oil-treated plots, respectively. Although population reductions in the lime treatment were significant in the second year, the effect was at a much reduced level in comparison to the two oil treatments. The overall results suggest that used motor oil and cotton seed oil may have potential for the control of apple clearwing.