Background: The sewer cockroach is one of the important pests in the health sector due to the microorganisms they carry in their bodies, contaminate food, and mainly affect the respiratory tract. Most chemical insecticides applied to control this pest affect people’s health and in addition to the fact that cockroaches have already become resistant to many of these products. An environmentally friendly alternative in pest control is the use of aromatic plants. The repellency of residual oregano hydrosols from three municipalities of Durango was evaluated in this research. The control groups drank drinking water, and the test groups oregano hydrosols. Insect survival was monitored daily for four weeks.

Results: The survival results were successful for the hydrosols of similar chemical composition from Mezquital and Nombre de Dios. These hydrosols additionally produced an insecticidal effect. The analysis of variance of the bioassays showed significant differences for a confidence interval of 95%. The results of the Kaplan-Miers survival analysis showed that oregano hydrosols with higher thymol content were more effective.

Conclusions: Oregano hydrosols (Lippia graveolens HBK) contain mainly thymol, are effective in controlling Periplaneta americana, and could reduce insecticide contamination