Plant-insect interactions involve interactions of great importance, such as pest management and plant pollination, because of their implications in crop yields. Inducible plant secondary metabolites, such as glucosinolates, can affect host-plant resistance and attractiveness to insects. Endophytic bacteria can also affect the interaction between plants and insects. This Special Issue Reprint presents a collection of papers on the interactions of insects with plants and highlights the importance of these interactions in pest management and pollination.