Even if you find a pheromone trail, it doesn’t tell you what direction is home, or what path to take at branching paths. You need dead reckoning. The trail just helps you reduce the complexity of what you have to remember.
You take the branch with the stronger smell to get home. The branching point is where the trail divides, as different groups branch out, and thus the way home has more pheromones. Follow the trail and you don't need to remember the direction...
Many animals detect and interpret smells as chemical gradients. We don't have the hardware for it, but plenty of others do.
