The Crop-Livestock Integration system has sustainable potential. But pests such as the defoliating caterpillar Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) can reduce the productivity of this system. The objective was to report transgenic maize and Brachiaria brizantha (A. Rich.) (Poaceae) plants attacked by S. frugiperda in the Crop-Livestock Integration system. Feroz VIP3 ® transgenic maize (SYN8A98 TLTG Viptera) and B. brizantha MG-5 Xaraés plants attacked by S. frugiperda were evaluated 20 days after planting, weekly and for 28 days. The transgenic maize plants were less attacked by S. frugiperda than those of B. brizantha. The negative impact of this pest on B. brizantha suggests the planning and adopting strategies for its control, such as the use of traps, resistant cultivars, and biological or chemical products, minimizing losses in animal production and, consequently, in human food.