Pseudalsophis biserialis is a diurnal and terrestrial snake that inhabits coastal volcanic rock areas, dry shrublands, dry grasslands and seasonally dry forests. During daytime, especially between 8:00 am and 5:00 pm, these snakes are typically seen swiftly moving on soil, leaf-litter and rocks. Galápagos racer snakes in general are mildly venomous, which means they are dangerous to small prey, but not to humans. They are active foragers and their diet includes geckos (Phyllodactylus baurii), lava lizards (Microlophus grayii), invertebrates, and birds. There are recorded instances of predation on juveniles of this species by centipedes of the genus Scolopendra.