Twospotted spider mites, Tetranychus urticae, are serious pests of many crops throughout the United States. Whenever hot, dry weather persists, large spider mite populations may develop on both soybean and corn. Producers in areas of Iowa where the weather remains dry should be on the lookout for spider mite infestations. Dale Schwade (A and K, Lime Springs) reported a 20-acre soybean field with classic spider mite symptoms last week in Howard County.