Abstract: The effects of entomopathogenic nematodes and fungi native strains were evaluated in laboratory and semi-field assays against larvae and adults of oak xylophagous pests (Coleoptera: Cerambycidae, Buprestidae; Lepidoptera: Cossidae). Due to their biology and ethology, these insects are examples of pests for which the chemical control is not effective and risky, as it can cause problems to individuals as well as to the environment. For this reason, the potential use of entomopathogenic nematodes (EPNs) and entomopathogenic fungi (EPF) as biological control agents was evaluated in laboratory and semi-field conditions. Native strains of EPNs (Steinernema feltiae, S. carpocapsae and Heterorhabditis bacteriophora) and EPF (Beauveria bassiana and Metarhizium anisopliae) were used to control larval and adult stages of four xylophagous pests (Cossus cossus, Cerambyx cerdo, C. velutinus, Coroebus florentinus). All the entomopathogens demonstrated the ability to control these pests. Beauveria bassiana and Steinernema feltiae caused significantly greater mortality rate in the adults and larvae than Metarhizium anisopliae, S. carpocapsae and H. bacteriophora. Nematodes and fungi are able to penetrate the cryptic habitats because they are living organisms and may be horizontally transmitted by infected hosts. The distribution of EPF as preventive control method and the injection of EPNs suspensions to reach and infect the larvae inside the wood galleries can be a combined sustainable control system. Some speculations or the symbiosis that can arise between xylophagous insects and pathogens are also presented: in these insect/pathogen relationships the insects can play an important role as vectors transporting pathogens.