Origanum floribundum Mumby is a rare aromatic and medicinal plant endemic to Algeria, belonging to the Lamiaceae family. The species grows spontaneously in pastures and especially in mountains up to 1500 m. The present work consists of an extraction, physicochemical characterisation and study of the insecticidal effect of the essential oil on chewing lice of the species Bovicola caprae. The essential oil was obtained by hydro-distillation using a Clevenger type apparatus. The yield of essential oil was around 1,86%. The results of the physico-chemical analysis show that the essential oil has a refractive index equal to 1,492, a relative density equal to 0,9539, a rotatory power equal to + 0,003 ° ± 0.00047 and a pH equal to 6,058. Analysis of the essential oil showed that its physicochemical properties comply with AFNOR standards. The toxicity of the essential oil was assessed by contact inhalation. 100% mortality insect mortality was recorded after one hour's exposure to a concentration of essential oil concentration of 0.8µl/ml.