In the insect world, smells are important. Insects of course do not have noses, but they do have receptors on their antennae, feet, and other body parts that allow them to sense chemicals and odors.
Female parasitoid wasps and flies are known to hone in on their hosts (caterpillars, cicadas, and other insects and arthropods) by "smelling" them -- that is, they sense chemicals from other insects that attract them. Once they find the hosts, they lay eggs on or inside them, and the young that emerge from the eggs feed on them.