Food trap investigations on stored-product insects in rice storages, farmers' warehouses, seed storages and rice mills in Thailand, revealed two contrasting types of population change of stored-product insects : suppression and explosive outbreak. Frequently the infestation levels in the rice storages were very low. The analysis of the factors that influenced the insect populations indicated that the suppression was apparently caused by natural enemies, especially predators. Many ants were captured such as Crematogaster sp.,Tapinoma indicum and Paratrichena longicornis. Xylocoris flavipes, a predacious bug and Withius niger, a pseudoscorpion were also trapped. In addition, the occurrence of intruders like spiders, lizards, etc. was frequently observed in the storage facilities since common rice storage structures in Thailand are widely exposed to such predators from outside. Thus, insect pests, natural enemies, especially predators from outside and host grain form a very unique and balanced ecosystem.