Defecation is an important physiological processes in insects which not only eliminates digestive waste, but can also release semiochemicals that play a role in intraspecies or interspecies interactions. Insect frass semiochemicals affect intraspecies’ aggregation, calling behavior and oviposition. Host semiochemicals are used by predators and parasites to locate and identify prey and hosts, respectively, and inhibit the feeding behavior of phytophagous insects by inducing plant defenses. This paper classifies and summarizes semiochemicals in insect frass based on published domestic and foreign research, and introduces their application in IPM. Problems in this field are discussed.