Insect eggs deposited on plant leaves are recognized and induce defenses that inhibit egg development or attract egg predators. Oviposition by the Large White butterfly Pieris brassicae leads to salicylic acid accumulation and local cell death in Arabidopsis thaliana. These responses are activated by a phospholipid elicitor perceived at the cell surface and share molecular similarities with generic innate immunity. Surprisingly, we discovered that oviposition inhibits growth of bacterial and fungal pathogens through the establishment of an intra- and interplant systemic acquired resistance (SAR). This finding suggests that eggs manipulate plant signaling by increasing resistance to pathogens, for the potential benefit of feeding larvae.