Does Cedar Mulch Repel Insects?

While cedar mulch does not seem to kill or harm insects, some insects are repelled by it, making it an effective way to control insect populations in lawns and gardens.

In a study done by the Department of Entomology at North Carolina State University, scientists found that the Argentine ant was less likely to create nests using cypress mulch. The scientists also found that trees surrounded by cedar mulch had fewer ants on them than trees that were surrounded by cypress mulch.

Barb Ogg, an educator at the University of Nebraska Cooperative Extension, says that the odor of cedar wood can repel termites. A study done by Mary L. Durea at the University of Florida IFAS Extension makes the same claim. In her study, she found that termites were less likely to eat mulch if it contained a small amount of heartwood red cedar.

While cedar mulch is an effective repellent against some insects, other forms of cedar are not. Cedar balls or cedar-lined chests may smell nice, but according to retired entomologist Jack DeAngelis, they do little to actually stop moths and other insects from infesting and laying eggs in clothes.