Resumo. Green lacewings (Neuroptera: Chrysopidae) are predatory insects during their larval stages, feeding on a variety of insect pests including psyllids, miner bugs, whiteflies, mealybugs, and the eggs and larvae of lepidopterans. These predators are integral to various agricultural systems. Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera: Noctuidae), commonly known as the fall armyworm, is a significant corn pest in Brazil and damages other crops like soybeans, cotton, and tomatoes. To control this pest, strategies such as Bacillus thuringiensis Berliner, 1915 (Bt)-based bioinsecticides and Bt transgenic plants are used. However, the rapid development of resistance hinders control, making the integration of different management tactics essential. This study examines the impact of the Bt-based bioinsecticide on the predatory behavior of the first, second, and third larval instars of Ceraeochrysa cincta (Schneider, 1851) (Neuroptera: Chrysopidae) through functional response analyses, using neonate S. frugiperda larvae as prey. Distinct functional responses were observed among larval instars. First-instar larvae exhibited a Type III response in both control and Bt-based bioinsecticide (Crystal®) treatments. In contrast, second- and third-instar larvae showed a Type I response in the control and a Type III response under bioinsecticide exposure. The highest attack rates occurred in first- and third-instar larvae in the control treatment, while handling time did not differ among instars or treatments. In conclusion, although the Bt-based bioinsecticide altered the functional response pattern of second- and third-instar larvae, it did not compromise the overall predatory capacity of C. cincta, supporting its compatibility with integrated pest management programs against S. frugiperda.