Root-associated entomopathogenic fungi (R-AEF) manipulate host plants to attract herbivorous insects. This study evaluated the behavioral responses of cabbage root flies to host plants with and without the R-AEF Metarhizium brunneum. Experiments on leaf reflectance, phytohormonal composition, and host plant location behavior showed that R-AEF inoculation decreased leaf reflectance in the near-infrared spectrum and increased the production of jasmonic acid, (+)-7-iso-jasmonoyl-L-isoleucine, and salicylic acid. In both greenhouse and field settings, cabbage root fly females showed increased landing and oviposition on R-AEF-inoculated plants. The fungal-induced changes in leaf reflectance may have altered visual cues used by the flies in host selection. This is the first study providing evidence that R-AEF manipulate host plants to attract herbivorous insects. R-AEF can be plant endophytes and soil saprophytes, and some have been reported to reduce herbivore damage by direct insect infection. They are commercially available for arthropod pest management in various cropping systems. R-AEF can increase host plant resistance to arthropod herbivores by triggering plant-induced systemic resistance or producing secondary metabolites that deter herbivorous insects. However, this concept remains speculative, and more complex interactions involving R-AEF and host plants can be expected. The study found that R-AEF inoculation significantly increased the likelihood of cabbage root fly larvae being infected. The findings suggest that R-AEF manipulate host plants to attract and infect insects, supporting the hypothesis that R-AEF can influence herbivorous insect behavior. The study also highlights the complex interactions between plants, root-inhabiting fungi, and insect herbivores, and the potential for R-AEF to be used as a biological control agent. The results demonstrate that R-AEF can alter host plant traits, which may increase susceptibility to herbivore attack, but could also benefit the fungi by increasing their dispersal. The study provides new insights into the functional roles and strategies of entomopathogenic fungi in tri-trophic interactions.Root-associated entomopathogenic fungi (R-AEF) manipulate host plants to attract herbivorous insects. This study evaluated the behavioral responses of cabbage root flies to host plants with and without the R-AEF Metarhizium brunneum. Experiments on leaf reflectance, phytohormonal composition, and host plant location behavior showed that R-AEF inoculation decreased leaf reflectance in the near-infrared spectrum and increased the production of jasmonic acid, (+)-7-iso-jasmonoyl-L-isoleucine, and salicylic acid. In both greenhouse and field settings, cabbage root fly females showed increased landing and oviposition on R-AEF-inoculated plants. The fungal-induced changes in leaf reflectance may have altered visual cues used by the flies in host selection. This is the first study providing evidence that R-AEF manipulate host plants to attract herbivorous insects. R-AEF can be plant endophytes and soil saprophytes, and some have been reported to reduce herbivore damage by direct insect infection. They are commercially available for arthropod pest management in various cropping systems. R-AEF can increase host plant resistance to arthropod herbivores by triggering plant-induced systemic resistance or producing secondary metabolites that deter herbivorous insects. However, this concept remains speculative, and more complex interactions involving R-AEF and host plants can be expected. The study found that R-AEF inoculation significantly increased the likelihood of cabbage root fly larvae being infected. The findings suggest that R-AEF manipulate host plants to attract and infect insects, supporting the hypothesis that R-AEF can influence herbivorous insect behavior. The study also highlights the complex interactions between plants, root-inhabiting fungi, and insect herbivores, and the potential for R-AEF to be used as a biological control agent. The results demonstrate that R-AEF can alter host plant traits, which may increase susceptibility to herbivore attack, but could also benefit the fungi by increasing their dispersal. The study provides new insights into the functional roles and strategies of entomopathogenic fungi in tri-trophic interactions.