What Scents Do Roaches Not Like?
Studies have shown that catnip, mint oil, citrus oil and orange oil are all effective means of controlling roaches. All are safer than commercial sprays.
Studies have shown that catnip, mint oil, citrus oil and orange oil are all effective means of controlling cockroaches. Using natural oils avoids the harmful effects of commercial insecticides on your family and your pets. Roach control also necessarily involves cleaning your entire home regularly and paying special attention to your kitchen and bathroom. You should vacuum frequently, but keep in mind that roaches can survive being vacuumed – especially if they are inside their mother's egg case – and may reappear at the first sign of food. To prevent this, be sure to discard the contents of the vacuum bag in a safe place far from your home as soon as you've vacuumed.
Nepetalactone in Catnip
Catnip can be an effective insect repellent. The feline intoxicant contains a chemical called nepetalactone, which can keep insects at a distance without harming humans or pets. Use catnip to repel roaches by leaving small bags of the herb in infested areas. You can also make a tea by simmering the plant in a small amount of water. Use a spray bottle to apply it to baseboards and other areas where you see roaches.
In 2001, Arthur Appel, Michael Gehret, and Marla Tanley used corn mint (Mentha arvensis L.) oil diluted in acetone to kill American and German cockroaches. The scientists found that it took less time for both species of roaches to die when they were exposed to higher concentrations of the mint oil. They published their findings in the Journal of Agricultural and Urban Entomology. The takeaway for the homeowner trying to control roaches is to use this oil generously – don't skimp.
Essential Oil of Citrus
Kaffir lime leaf (Citrus hystrix DC) oil can effectively repel American, German and harlequin cockroaches, according to a study conducted by Usavadee Thavara and colleagues in 2007. The team of researchers diluted the citrus oil in ethanol at various concentrations and found that it repelled 100 percent of American and German cockroaches and 87.5 percent of harlequin species. They published their findings in the Southeast Asian Journal of Tropical Medicine and Public Health.
Osage Orange Oil
The Osage orange tree (Maclura pomifera) bears yellow-green, grapefruit sized fruit that are often called hedge apples. The fruit is a popular insect repellent home remedy. Some people place it in basements, near baseboards and around the foundations of their homes to repel roaches and other insects, such as spiders and crickets. Sesquiterpenoid is the aromatic component of hedge apples, and it may be responsible for the fruit's repellent effects. Cockroaches exposed to areas painted with the oil from Osage oranges moved to untreated areas, according to Jennifer Schultz Nelson, a horticulture extension educator with University of Iowa. However, she added, studies of this material were conducted with oil extract, rather then fresh fruit, and were quite limited.
- Iowa State University: Facts and Myths Associated with Hedge Apples
- CBS News: Cat's Bliss Is Roach's Blight
- Journal of Agricultural and Urban Entomology; Repellency and Toxicity of Mint Oil to America; Arthur G. Appel, et al; n and German Cockroaches (Dictyoptera: Blattidae and Blattellidae); 2001
- Southeast Asian J Trop Med Public Health: Repellent Activity of Essential Oils Against Cockroaches (Dictyoptera: Blattidae, Blattellidae, and Blaberidae) in Thailand
- University of Illinois: Osage Orange Maclura pomifera
- Baltimore Sun: What Cats Love, Roaches Loathe
Based in North Carolina, Nigel Wall has been writing science and health-related articles since 2001. Her articles have appeared in scientific journals like the "Journal of Medical Genetics" as well as on various websites including Betterdigestion.org and 1Degreebio.org. Wall holds a Master of Science in biotechnology from Johns Hopkins University.