The answer to 'wasp trails' is that wasp trails are a sign of an active wasp nest nearby. Wasps leave a pheromone trail as they travel back and forth from their nest to food sources, which can create visible trails on surfaces like walls, windows, or eaves. These trails are a clear indicator that you have an active wasp nest that needs to be addressed.
Wasp trails are a symptom of a larger problem - the presence of a wasp nest. While you may be able to temporarily remove the trails, the underlying issue of the nest will remain and the wasps will continue to create new trails. For a long-term solution, it's best to have a professional pest control technician locate and safely remove the nest to eliminate the wasp problem at its source.