Red palm weevil (R.P.W.) R. ferrugineus (Coleoptera: Curculionidae) is the main date-injury palm insect in Egypt. This insect became the most destructive pest for date palms. All research seeks out safe methods for controlling this pest. This study aims to use eco-friendly and safer methods to manage R.P.W. However, the effect of Formaldehyde needs more research. The phrase "formalin" refers to the gas formic aldehyde, CH2O, which is a 40% solution of Formaldehyde in water. The results showed that concentration (40%) had a significant impact on larvae in their second instar and newly hatched red palm weevil among all concentrations after exposure to a toxic zone for ten days. The results revealed that there was an increase in larvae mortality by increasing the duration of exposure to Formalin, and this may depend on the accumulation of Formalin on target organs. Data reported that Formalin is effective for the larvae. So, Formalin could interrupt the life cycle of red palm weevil and might be suitable for integrated pest management of this pest as a protective or curative agent. In terms of LC50 and LC90, the relative toxicity of the tested concentrations at the LC50 and LC90 levels showed that the toxicity of Formalin on newly hatching was the most effective among other larvae of red palm weevil. Regarding LT50 and LT90 values, formalin application demonstrated great activity against R. ferruginous, and the needed time causing 50 and 95% mortality (LT50 and LT90) decreased when the formalin concentration increased.