Insecticide resistance in the lesser mealworm, Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae), can pose a serious threat to their successful management in broiler chicken farms in Arkansas. Resistance and cross-resistance were determined in lesser mealworm populations collected from two broiler farms in Arkansas, with different insecticide application histories. Farm M was treated with insecticides over the past 10 yr, whereas Farm S had no insecticidal usage history. Concentration—mortality bioassays using selected insecticides were conducted on adults and seventh-instar larval beetles. A probit analysis suggested the M population to be resistant to cyfluthrin and tetrachlorvinphos, while the S population was susceptible to both compounds. The M population showed no crossresistance to imidacloprid, spinosad, or chlorfenapyr. TheMand S populations were similar in their susceptibility to imidacloprid, spinosad, and chlorfenapyr. The suitability of imidacloprid and spinosad, and further testing of chlorfenapyr as a potential candidate for lesser mealworm control is discussed.