What Scents Do Roaches Not Like?

By Nigel Wall
Cockroach repellent doesn't have to be harmful to humans and pets.

Roaches are pesky little creatures that can multiply to out-of-hand numbers quickly, so control requires immediate action. Cleaning your entire home regularly and paying special attention to your kitchen and bathroom is a must. Vacuuming frequently is also helpful, though roaches can survive being vacuumed -- especially if they are inside their mother's egg case -- and may reappear at the first sign of food. If you are concerned about the harmful effects of commercial insecticides, you may be successful using some natural scents that help keep roaches at bay, while keeping family members and pets healthy as well.

Nepetalactone in Catnip

In 1999, two Iowa State University scientists, Chris Peterson and Joel Coats reported that catnip is an effective insect repellent. A chemical called nepetalactone is found in the catnip plant and is responsible for its repellant effects. This chemical is not harmful to pets and humans. Leave small bags of catnip in roach infested areas to repel the insects. You can also make a tea by simmering the plant in a small amount of water and using a spray bottle to apply it to baseboards and other areas.

Mint Oil

In 2001, Arthur Appel, Michael Gehret, and Marla Tanley published findings in the Journal of Agricultural and Urban Entomology concerning the repellent and toxic effects of mint oil to American and German cockroaches. They used corn mint (Mentha arvensis L.) oil that was diluted in acetone for this experiment. 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.

Essential Oil of Citrus

In 2007, Usavadee Thavara, Apiwat Tawatsin, Payu Bhakdeenuan and their colleagues published findings in the Southeast Asian Journal of Tropical Medicine and Public Health stating that kaffir lime leaf (Citrus hystrix DC) oil is most effective in repelling American, German and harlequin cockroaches. The citrus oil was diluted in ethanol at various concentrations. The oil repelled 100 percent of the American and German cockroaches and 87.5 percent of the harlequin species.

Osage Orange Oil

The Osage orange tree (Maclura pomifera) bears yellow-green, grapefruit sized fruit that are often called hedge apples. It is a popular insect repellent home remedy. Some people place the fruit 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 that may be responsible for its 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.

About the Author

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.