Did I just write the heading, possible snake repellents? Doesn’t that statement conflict with an earlier blog post about the relative inadequacy of mothball-based snake repellents, see Snake Repellents? Well the short answer to all that is, “Yes, but with a caveat.” An interesting article by Larry Clark and John Shivik, entitled, Aerosolized essential oils and individual natural product
compounds as brown treesnake repellents, published in 2002, in the Pest Management Science journal (58:775-783, DOI: 10:1002/ps525) shed some interesting light on several possible snake repellents.
Clark and Shivik’s Article in Brief
Brown tree snakes (Boiga irregularis) are an invasive (and dangerous) species that since their introduction to the island of Guam have been responsible for significant declines in the island’s native bird species. Since officials want to avoid transporting these snakes to other islands, finding an effective repellent would be an important tool in the tool box for managing this dangerous species. Since the cost of registering a non-food based repellent with the EPA is enormous, these scholars sought to evaluate essential oils. Essential oils, many of which are already used in food or air fresheners would require a lower barrier to EPA registration.
Clark and Shivik investigated the effect of 14 essential oils not counting water on snakes followed by an analysis of 20 specific chemicals which were key components of those essential oils. Essentially the test was as follows. First snakes were tested to see if they reacted to a squirt of water. If they didn’t react they were used in the study. Reactions were evaluated as either vigorous motion, slow motion or no motion. Vigorous motion was when the snake reacted violently to the sprayed oil or chemical. Slow motion was the snake’s reaction was more investigative as if it was trying to look around. No motion should be self explanatory.
Results of the Snake Repellent Study
The authors found that snakes reacted significantly to cedarwood, cinnamon, sage, juniper berry lavender and rosemary oils. As for individual chemicals, snakes reacted vigorously to aerosols of m-anisaldehyde, trans-anethole, cineole, cinnamaldehdyde, citral, ethyl phenylacetate, eugenol, geranylacetate or methyl salicylate.
Before you go out and buy some essentials and start offering snake repellent services, you need to keep a few things in mind.
- These products were tested on brown tree snakes. Not garter snakes, etc. Does that matter? It might.
- None of these products/chemicals have been registered by the EPA for use as snake repellents. Don’t break the law!!!
- None of these products were tested as barrier repellents. Meaning, they weren’t tested to see if a snake would avoid an area with these chemicals. The authors noted that these chemicals may be better characterized as flushing agents. In other words, these products may find a use as a way of seeing if a snake is present in a shipping container or crawl space. Fog the space and see if the snake emerges or shows himself. While developing flushing agents can be important for WCOs or PCOs, they are unlikely to do much for the bottom line even if the EPA did register them. So patience folks. As of this blog, there are no known barrier chemical repellents yet, at least for American snakes, that I know of. The search and the wait continues.