In the last decade there has been increased focus on the potential of endophytic Beauveria bassiana for the biocontrol of insect herbivores. Generally, detection of endophytes is acknowledged to be problematic and recovery is method-dependent. Herein, we critically analyse the methodology reported for the detection of B. bassiana as endophytes following experimental inoculation. In light of the methodology, we further review the effects of endophytic B. bassiana on insect herbivores. Our review indicated the need for stringent protocols for surface sterilisation including thorough experimental controls. For molecular detection protocols by PCR, residual DNA from surface inocula must also be considered. The biocontrol potential of B. bassiana endophytes appears promising although both negative and neutral effect on insect herbivores were reported, however, there remains ambiguity with respect to the location and mode of action of the fungus in planta. We recommend that future studies should adopt multiple techniques, both culture dependent and independent, for endophyte detection and elucidate the mechanisms involved against insect herbivores.