The answer to 'why is my spider trails' is that spider trails, also known as web trails or drag marks, are a common sign of a spider infestation in your home. Spiders leave these trails as they move around, leaving behind silk strands that can be visible on surfaces like walls, floors, and furniture.
Some common causes of spider trails include an abundance of insects for the spiders to feed on, dark and undisturbed areas that spiders prefer, and gaps or cracks in the home's exterior that allow spiders to enter. Seeing spider trails is often an early indicator of a larger spider problem that may require professional pest control intervention.