DEHP is a widely produced plasticiser found in the environment, in particular in sediments, soils and plants. Few studies have focussed on its effects on terrestrial insects. We used the leafworm Spodoptera littoralis o study the effects of DEHP on post-embryonic development, male sexual behaviour and offspring's development. Larvae were exposed to environmentally relevant concentrations and higher concentrations of DEHP via food. An integrative approach was used, combining post-embryonic and male sexual behaviour monitoring, ecdysteroid and DEHP titration, gene expression measurements and metabolomics.