Blind snakes prey upon and travel with army ants. These snakes are attracted to army ant worker secretions, which may originate in the head and be deposited with the ant trail pheromone. The army ant secretions, especially skatole, repel certain ophiophagous and insectivorous snakes. Similarly, the blind snake cloacal sac substance, known to repel army ants, also repels sympatric ophiophagous and insectivorous snakes. Blind snakes are attracted to their own cloacal sac substance. The function of intraspecific attraction is viewed as most important in this complex system of chemical regulation. Interspecific attraction and repulsion is secondary. For blind snakes, the repulsion of their predators and competitors may be more important than repulsion of ants.