Macrophages are present in various forms throughout metazoans and play conserved roles in phagocytosis, immunity, and tissue homeostasis. In Drosophila melanogaster' s larval hematopoietic organ, the lymph gland, transient caspase-mediated activation of caspase-activated DNase triggers the DNA damage response (DDR), which is crucial for macrophage-type cell differentiation. Here, we report that other Drosophila species having different-sized mature lymph glands show effector caspase activity and DDR similar to those in Drosophila melanogaster , indicating that the developmental mechanism regulating phagocytic macrophage differentiation is conserved in different species of Drosophila .