Some of the creepiest bugs that share living space with humans belong to a group of arthropods often grouped under the title of silverfish. Four types of silverfish and a fifth arthropod, Scutigera coleoptrata, actually a house centipede, scuttle with amazing speed and are customarily nocturnal. If you find one in the tub, it can be unsettling. Sanitation and a dehumidifier are most effective in keeping populations low, but you can also build your own silverfish traps to catch the critters.
Wind masking tape around six or more shiny clean glass jars and put a bit of sugar or school paste in each. Alternately, purchase silverfish and spider traps available at a hardware or home store. Spread the traps out near bookshelves, heating ducts, plumbing; any place warm and moist is a likely source of infestation.
Keep track of how many victims each trap catches and move them around until you pinpoint the route silverfish are using to get into the house. Odds are, the creepy crawlies you find in the tub crawled to the top, fell in and simply couldn't climb up the slick sides to get out.
Clean out the floors of closets. Remove corrugated or cardboard storage boxes in damp, warm areas and empty them of their contents. Launder or vacuum contents and repack in sealed plastic storage bags and tubs. Seal infested books or papers in plastic bags and store them in the freezer for at least three days to kill the silverfish.
Put on goggles and mask. Blow boric acid, silica gel, diatomaceous earth or other dust designed for use on silverfish or house centipedes carefully into crevices or gaps under woodwork with an aspirator or bulb duster.
Use a dehumidifier in moist areas such as bathrooms and basements to discourage nocturnal visits from silverfish and their relatives.