British researchers report that two common essential oils—tea tree and lavender—show promise in treating lice that are increasingly resistant to commercial pesticides.

Found primarily on donkeys and horses, Bovicola ocellatus are known as “chewing lice” because they feed on dander rather than drawing blood meals. For their study, University of Bristol researchers identified 198 barn-kept donkeys infested with B. ocellatus.

After initially quantifying the level of each animal’s parasite load, the researchers divided the donkeys into three treatment groups: One received two topical treatments with a 5 percent tea tree oil solution two weeks apart; the second received two topical lavender oil treatments at the same interval; the third group was treated with an inert substance to serve as controls.

When each animal was again evaluated at the end of the study period, the researchers found a dramatic decline in the level of infestation among both groups treated with tea tree oil or lavender oil. In fact, lice infestation on those animals declined by an average of 78 percent. In the control group, which received no treatment, lice populations either stayed the same or increased. 

The researchers conclude that essential oils can be an effective means of louse control.

Reference: “Essential oils in the management of the donkey louse, Bovicola ocellatus,” Equine Veterinary Journal, March 2015

Don’t miss out! With the free weekly EQUUS newsletter, you’ll get the latest horse health information delivered right to your in basket! If you’re not already receiving the EQUUS newsletter, click here to sign up. It’s *free*!