You’re brushing your teeth, barely awake, when something tiny, shiny, and incredibly fast suddenly darts across the bathroom floor. “Gross.” If you’ve experienced this more than once, you may be dealing with silverfish. These small, silvery insects are usually found in bathrooms, basements, laundry rooms, kitchens, closets, and other dark areas. They are mostly active at night and are easily recognized by their quick, wiggling movement.

Silverfish usually enter homes because they find the conditions comfortable. Moisture and humidity are the biggest attractions, especially around leaking pipes, damp walls, condensation, or poorly ventilated bathrooms. They also like dark, quiet hiding places such as cracks, closets, storage boxes, and spaces under sinks. Their food sources can include paper, cardboard, books, wallpaper paste, fabrics, starches, and some pantry foods. Seeing one does not necessarily mean your home is dirty, but repeated sightings can indicate that a nearby area is providing everything they need.

The good news is that silverfish are generally harmless to people and pets and are not known for biting or spreading diseases. However, they can damage books, documents, cardboard, wallpaper, clothing, and other stored materials. Look for shed skins, small droppings, yellowish stains, or irregular damage, especially in dark and humid areas.

The best way to get rid of silverfish is to remove the conditions attracting them. Reduce humidity with ventilation or a dehumidifier, fix leaks, keep paper and cardboard in dry places, clean crumbs, reduce clutter, and seal cracks around walls, windows, pipes, and baseboards. Sticky traps can also help determine whether silverfish are still active.

If silverfish keep appearing despite these changes, especially in several rooms, consider contacting a pest professional. The goal isn’t simply to kill the insects you see, but to make your home less comfortable for them. “Keep damp areas dry. Fix leaks. Reduce clutter.” These simple steps can go a long way toward preventing silverfish from coming back.