Is Orange Green?

Orange Oil for Drywood Termites, Marketing or Magic. (pdf)

Used by permission Florida Chemical Company Inc.

How is orange oil used to treat dry wood termites?

First of all, d-limonene, is aromatic, with some absorbing qualities. There is no scientific evidence indicating that it "penetrates the wood to kill termites as some advertisements claim. "Of course anything other than direct contact would result in no mortality of I. minor. At best it is a very, very local fumigant (a few centimeters) when high vapor concentrations are present in closed galleries."( Dr. Rudolf H. Scheffrahn University of Florida).

Unpublished research has determined that injecting d-limonene oil into termite galleries can kill dry wood termites. The problem with this method is, drill and injection is a random, localized treatment and not whole structure. The limitations would include the many "inaccessible areas" common in most structures and detection.

Detection

Detecting live termite infestations is critical for efficacy of spot treatment with d-limonene or any other product. One cannot inject a liquid into solid wood; the liquid would have to be injected into a termite gallery. If there happens to be termites it that gallery, orange oil as a contact poison would offer reasonable control (UC Davis IPM 2006). Undetected termites will not be treated. The elusive drywood termite cannot be detected in wood by the naked eye. There are devices on the market for detecting termites. They include: Acoustic Emission Devices (Termite Tracker), odor detectors and fiber optics. "These devices are expensive, lack adequate field studies and are rarely used" (Lewis, Vernard 2002 Drywood Termite Pest Notes). However, Dow Chemical has published studies on Acoustic emission devices: They worked with PCOs in actual field situations. Thoms, 2000. Fla Entomol. 83:64-74. They used acoustic detectors to evaluate the treatment of drywood termites with spinosad. They found better than 90% mortality at 89% of the sites. No tests were done with d-limonene. Because of design and intent of an infested structure, termite galleries can extend into wood framing behind sheetrock or tiled walls. This condition would create inaccessible areas for treatment and detection. Subsequently, one would have to gain access to infested areas by removing wall covering or other expensive renovation. In addition, orange oil offers no residual qualities (<24hours). Termites will not feed on wood treated with any type of oil (Rust, UC Irvine) these conditions could allow termites to move to other areas of the structure.

Is orange oil magic?

Orange oil can kill termites. It is considered a low toxic product and efficacious when used under optimum conditions. It is definitely, not magic and not the best product on the market. "There are no residual qualities, has odor that lingers that many people do not habituate to, flammable, and, as an organic solvent, will damage many painted and finished surfaces. (dr. schefferhan)

Unlike heat treatments, the electro gun, and low toxic, non repellent liquid residuals that went through rigorous independent university studies (Vernard R. Lewis, Michael I Haverty) there is no empirical data or published reports on the efficacy of Orange oil. Dr. Michael Rust of UC Irvine and Dr. Rudolf Scheffrahn of University of Florida have done some independent testing.

The below is their response to customer Molly M. of Sebastopol:

From Dr. Michael Rust of UC Riverside.

I don't know of any published studies regarding d-limonene against drywood termites. We have done some laboratory testing, but it is not complete. The d-limonene will kill termites on contact, but has very little residual effect (< 24 hours). Termites will not feed on wood treated with oils including olive oil, canola oil, ect. We don't know how far the effect extends.

The problems with localized chemical treatments are the detection and treatment of individual colonies. If colonies are not detected or inaccessible, they will not be killed by injecting chemicals. In widespread infestations, the fumigant (Vikane or sulfuryl fluoride) or the heat treatment is probably a better option.

Without the scientific studies, it comes down the buyer beware. Unfortunately, the companies that registered the d-limonene were not required to produce field efficacy data to get it approved.

"Limonene is a contact poison to termites. The issue is that if the colony or colonies are not accessible to treatment with limonene, there will be no success. On the other hand, the fumigant will kill termites in all parts of the structures. What are your objections to fumigation? Maybe those can be addressed to determine your best option."

Rudolf H. Scheffrahn
Professor of Entomology
University of Florida

Orange alone is not Green

The Pest control industry should be proud of recent innovations and less toxic treatment methods. There is no need to misrepresent products, use unreasonable scare tactics and resort to questionable and even illegal claims. Being "green" is much more complex than a "one size fits all" approach in dealing with termites. Every situation is different and control would have to be accomplished in a "prescribed" manner. Integrated pest management (considered a green approach to pest control) is an inclusive process focusing on not only the pest problem but also the issues regarding "the reason" for the problem. Hence, coming up with permanent or long-term reduction in the target pest population. These solutions may involve habitat modification, structural modification, physical control, cultural control and judicious use of pesticides. Treatment also involves understanding the biology of the pest and a working relationship with a proactive homeowner.

There is strong public interest in reducing the presence of pesticides in our environment. People are demanding less exposure to all types of toxicants, not just pesticides. By providing accurate information, and excellent customer service, pest management professionals will best represent our industry.

UC Davis IPM program
Pest Control Operators of California
Evaluation of Six Techniques for Control of the Western Drywood Termite (Isoptera: Kalotermitidae) in Structures - Vernard R. Lewis and Michael I. Haverty
Alternative Control Strategies for Termites - Vernard R. Lewis
Rudolf H. Scheffrahn, Professor of Entomology University of Florida,
non-published studies on orange oil - Michael Rust, UC Irvine
Florida Chemical Co Inc.

Bill Mashek
BS, Biology, Teaching Credential Dominican University
Advanced Urban Integrated Pest Management graduate, Perdue University
Principal, Northwest Termite and Pest Control Inc. Specializing in least toxic termite and pest control.