Cyromazine is a triazine molecule with insect growth regulator properties being developed for control of Colorado potato beetle (Leptinotarsa decemlineata Say) (CPB) in vegetables. Research presented focuses primarily on results with potato (Solanum tuberosum L.), however, crop safety has been observed in other crops within the Solanaceae. Several trials were conducted in PA and NY during 1991 to examine the rates and timing necessary to control CPB in potatoes. Data from replicated small plot trials and non-replicated large block trials are included. Rates examined ranged 70 to 560 g ai na-1 applied alone or in combination with a pyrethroid or Bt. Comparisons were made with insecticides presently registered for CPB control in potatoes and cyromazine compared quite favorably. Two applications per CPB generation were made, the first at the beginning of CPB egg hatch and a second 7-16 days later for each generation. This application schedule provided excellent (90%) control of CPB larvae. The reduction in larvae also resulted in a reduction in adult CPB and potato leaf area damaged through insect feeding. In the test conducted in PA, an increase in size and number of tubers was observed when plants were treated with cyromazine. -These increases resulted in a 23-28% increase in total yield compared to that obtained from the untreated check plots.