Within the social framework of lower Isoptera, termite soldiers are traditionally known for their role in providing defense against potential enemies. While it is apparent that soldiers protect the colony, evidence also suggests that they play a role in caste differentiation. Past research has shown that the presence of live soldiers and extracts from soldier heads inhibit the formation of new soldiers. In contrast, treatments of juvenile hormone III (JHIII) have been shown to induce soldier formation. What remains unclear is whether an interaction exists between termite soldiers, extracts from soldier heads, and JHIII on nestmate caste differentiation. Thus, the goal of this study was to clarify the effect of soldier head extract (SHE) on worker caste differentiation, and to investigate the potential interaction between SHE and JHIII on worker caste differentiation. Results from model bioassays indicate that extracts from soldier heads, applied in combination with JHIII, synergistically increased worker-to-presoldier morphogenesis, while treatment of SHE alone caused no worker-to-presoldier morphogenesis. Additionally, experiments are currently being conducted to compare gene expression patterns of SHE and JHIII treated termites. These results provide a significant step toward understanding how termites modulate colony caste composition. These preliminary results suggest that soldier termites are likely using SHE and JHIII to regulate nestmate caste differentiation.