The book "Formosan Subterranean Termites: Understanding the Defense Mechanism" offers a comprehensive analysis of the biological control of Formosan subterranean termites (FST), particularly through the use of entomopathogenic fungi (EPF). Significant advancements have been made in this research area over the past two decades, and the monograph addresses various aspects of EPF, including their virulence and mode of action. Additionally, it thoroughly examines the biology, habitat, distribution, damage, and management options of FST. A central concern of the authors is to highlight the challenges associated with establishing self-sustaining EPF populations necessary to reduce FST densities to economically damaging levels. The research findings provide new insights into the behavioral, biochemical, and physiological adaptations of FST that contribute to combating EPF. This monograph is particularly valuable as it sheds light on the immune mechanisms of FST for the first time, which are regulated by a variety of genes involved in pathogen recognition, signal modulation, transduction, and the production of antimicrobial peptides (AMPs).