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Wireworms are important pests in potato crops. In Switzerland, the predominant species feeding on potato tubers are Agriotes lineatus, A. obscurus and A. sputator. After the withdrawal of the insecticide Fipronil in 2013, no highly effective products were available on the market for wireworm control. Therefore, we tested a number of synthetic insecticides applied as coatings of oat seeds to evaluate their efficacy in wireworm control. Two application timings were compared: (1) application in the potato ridges at planting in spring (2015 and 2016), and (2) application as green manure sown in late summer (prior to potato planting in 2016 and 2017). None of the tested products had a significant impact on the percentage of tubers damaged by wireworms with the exception of “Goldor Bait” (active ingredient: Fipronil) used as a reference product. The efficacy of “Goldor Bait” was higher with an application in fall (89.5%) as compared to an application in spring (53.0%). This indicates that the application timing is important to achieve the best possible efficacy.