The future of pest control may be a matter of leading animals by the nose. Pheromones -- the chemical secretions many species use to communicate with one another -- have proven highly successful in various kinds of insect lures. Recently, scientists have managed to crack two more of the animal world's nasal codes.

At Indiana University, chemist Milos Novotny has devised a mouse repellent that is pleasant-smelling to humans but sends a strong olfactory "keep out" warning to mice. Based on the pheromones that dominant male mice use to mark their territories, the scent reportedly sends potential rodent trespassers packing.

Meanwhile, an Agricultural Research Service scientist has identified a chemical that may lead to better control of the fire ant -- which has become a growing menace in the South, where it is feared for its painful sting and damage to crops and livestock. To date, toxic lures have not been fully effective because the ones now used also attract and poison the ants' natural enemies.

Now, however, chemist Robert Vander Meer of the Research Service's Gainesville, Fla., lab, has identified a pheromone specific to the fire ant -- one that carries the message: "Come help us carry this chunk of food." By synthesizing the scent and combining it with an insecticide, researchers hope to make a sure-fire ant trap.