In many North American homes, roaches are an unwelcome surprise that appear when the lights go out. You bleach your countertops, vacuum up crumbs and keep food sealed, yet somehow roaches still find a way in. They hide behind cabinets and appliances, coming out at night to feed. Their droppings and shed skins can contaminate food and trigger allergies. You might try aerosol sprays, glue traps or poison baits, but these methods offer only temporary relief and leave behind chemical residues. The l