The blind snakes, Leptotyphlops dulcis and Typhlops pusillus, readily follow pheromone trails of various ants and termites and their own trails plus those made by conspecific individuals. Conversely, the colubrid snakes, Sonora episcopa, Tantilla gracilis, and Virginia striatula, do not follow insect and snake trails as readily, although the latter two species follow army ant and earthworm trails, respectively. Army ant trails are followed much further by the blind snakes than trails of other ants. This behavior is selectively advantageous, since these trails can lead to both army ant and captured ant brood as food for the snakes. Blind snakes and colubrids follow the trails of individuals of the opposite sex further than their own trails or those of other members of the same sex. This behavior is selectively advantageous for reproduction. Also, snake trail-following may effect aggregations that conserve moisture and reduce temperature fluctuations. Pheromone trail-following in general is advantageous, as it reduces the energy spent foraging for food, shelter, and mates.