During the last few decades, we have faced problems caused by some invasive forest pests such as the black locust gall midge, spotted lanternfly, citrus flatid planthopper, pine wood nematode, etc. As for the pine wood nematode, it is originated from the US and found two insect vectors which previously were not considered as insect pests at all in Korea. Now those two Monochamus cerambycids are nothing but insect pests to be controlled in order to slow down the spread of the pine wood nematode. Here we introduce the results of the surveys seeking out parasitoids which can be used for biological controls against those pests. In addition we also make a suggestion to keep our efforts to utilize those beneficial insects as eco-friendly control measures, not simply depending on physical or chemical methods.