Insect eggs are not passive structures deposited on leaves. They induce plant defenses that inhibit egg development or attract egg predators. Oviposition by the Large White butterfly Pieris brassicae leads to salicylic acid (SA) accumulation and local cell death in Arabidopsis. These responses are activated by a phospholipid elicitor perceived at the cell surface and share molecular similarities with PAMP-triggered immunity (PTI). However, expression of defense genes regulated by the jasmonic acid (JA) pathway are suppressed and larval performance is enhanced. We also discovered that oviposition by P. brassicae inhibits growth of bacterial and fungal pathogens through establishment of an intra- and interplant systemic acquired resistance (SAR). Altogether, our results suggest that eggs manipulate plant signaling by inhibiting anti-insect defenses and increasing resistance to pathogens, for the potential benefit of feeding larvae.