Wood borers are important forest insect pests and difficult to control due to their concealed behavior. However, parasitic wasps can effectively ascertain and parasitize wood borers as well as other concealed pests using special searching, finding and attacking mechanisms, developed during the course of long-term coevolution with their hosts. The present paper summarizes the behavioral mechanisms of parasitic wasps involved in searching and locating their concealed hosts. Parasitic wasps can accurately find the location of their hidden hosts and then parasitize them, usually using olfactory semiochemicals from hosts (lavare and adults), host frass and symbiotic microorganisms in host galleries; visual signals from color contrast of plant surface; contact stimuli from characters of host physical defense; substrate vibrations produced by host feeding and movement, and infrared radiation from host activities and metabolizability. Some parasitic wasps may integrate the information of several stimuli from different sources for enhancing the reliability and accuracy of host locations. In addition, the potentials for utilizing their host location signals in biological control using parasitoids are discussed.