Finding a slug inside is unsettling, but it’s also a useful signal. Slugs are drawn to cool, damp, hidden routes, slipping through gaps beneath doors, along pipes, or through cracks near the foundation. Their presence often points to excess moisture, poor drainage, or unnoticed openings that have quietly developed over time. Instead of only scooping the intruder up with a paper towel and moving on, pause and study where it came from. Trace any silvery trail back toward door frames, baseboards, or plumbing penetrations, and then step outside to inspect soil, mulch, downspouts, and standing water around your home. By sealing gaps, improving drainage, and thinning dense vegetation against your walls, you’re not just stopping slugs—you’re protecting your house from rot, pests, and hidden damp. That unnerving slug on the floor might be the small, unpleasant warning that saves you from a much bigger problem later.