Insects use sensory cues to select plants for feeding and oviposition. For a better offspring survival and life-history performance, the oviposition-site selection by gravid females usually corresponds with plant suitability for the best offspring development. To test this, we used the three-component interacting system involving Botrytis cinerea, a pathogenic fungus on Vitis vinifera, and the plant-feeding Epiphyas postvittana. We hypothesised that the gravid females of E. postvittana discriminate between B. cinerea-infected and uninfected leaves of V. vinifera for oviposition to maximise their offspring performance. We characterised volatiles from B. cinerea-infected and uninfected leaves of V. vinifera. We tested the effect of volatiles from B. cinerea-infected leaves on the olfactory behaviour of E. postvittana using a wind-tunnel assay. We raised the neonate larvae of E. postvittana on B. cinerea-infected and uninfected leaves to characterise their development and life-history performance. The key volatiles from B. cinerea-infected V. vinifera leaves were 2'hexene-1-ol, 2-hexenal (E), 1-hexanol, 3-octanone, and 1-octen-3-ol, whereas the same leaves included highly reduced levels of nonanal, benzaldehyde, acetic acid, and hexanal. Results from the wind-tunnel assays showed that gravid females avoid infected leaves, suggesting that the induced and reduced volatiles, subsequent to infection, may be used as a signal in oviposition-site selection by E. postvittana. This is further confirmed by the total failure of our attempts to rear neonate larvae to adult on B. cinerea-infected leaves.