Cockroaches are an extremely common pest in buildings, especially ones not kept thoroughly clean. They are so numerous due to their prolific rate of reproduction. The sight of one roach will signal hundreds more hiding in wall crevices or under floorboards. Roaches can spread disease and bacteria to the occupants of a building, so they should be expelled as soon as possible. Certain scents can be used to drive away roaches as an alternative to killing them with pesticide sprays or bait.
Catnip is a perennial herb that can be grown in North American gardens. It contains nepetalactone, which is not poisonous to humans or large animals, but can be a chemical stimulant to cats. To make use of catnip as a roach repellent, place small sachets around areas where the insects have been observed. Alternatively, mix with a small amount of water to create "catnip tea." Spray in difficult to-reach places behind cupboards and cabinets.
Bay leaves contain natural insecticides, and their smell and taste is abhorrent to cockroaches. Crushed leaves, left scattered around all parts of a building where roaches have been seen, including inside wall crevices and under the sink, may well eradicate a small infestation. Leave the bay leaves in place until there are no more signs of roach activity. Bay leaves can be purchased from grocery stores and can even be boiled to make a "tea" for spraying the bugs.
The scent of lemon or orange-flavoured products in the air can kill roaches even up to four weeks after spraying. Lemon juice is an effective means of killing off an infestation when used to coat areas where roaches have been observed. A small amount of lemon juice added to water will either kill or deter roaches when used to mop the floor. Similarly, the peeled remains of an eaten orange or lemon may be left out to discourage them.
Roaches will avoid red pepper at all costs. A popular remedy for repelling them is to mix a tablespoon of red or cayenne pepper with a mashed garlic clove and one white onion in one quart of boiling water. After letting it cool down for an hour, pour the liquid result into a spray bottle and apply in roach-infested areas.
Cockroaches don't like the scents of rosemary, cedar or eucalyptus oils. Place a few drops of these essential oils on cotton balls and place them in close proximity to the roach-troubled area in order to repel the creatures. Reapply the oil to the cotton every couple of days so the scent remains potent.