The corn wireworm, Melanotus communis Gyllenhal, is a serious pest of several agricultural crops including corn (Zea mays L.). Numerous studies have been reported on wireworm control at crop planting including the use of seed treatments. However, there are no published reports on the efficacy of corn seed treatments for wireworm control. The objective of this study was to determine efficacy and mode of action of various corn seed treatments against M. communis. Wireworms (larvae) were collected by digging under sugarcane stools in Florida. Testing was conducted in plastic buckets which contained soil, insecticide-treated seeds, and six wireworms per bucket. Buckets were held at 24°C for 1 mo and then plant growth and insect survival were measured. Wireworms were also held an additional month to measure possible delayed mortality. Treatments with insecticides or the fungicide Maxim Quattro (Syngenta Crop Protection, Inc., Greensboro, NC), or both, in various combinations and rates, all had greater emergence and significantly greater plant vigor, height, and weight than did controls. However, many wireworms were also alive, active, and completing development in all treatments after 2 mo. These data are consistent with the growing recognition that in many cases plant protection from wireworms may be obtained through nonlethal means.