The reduction in the susceptibility to deltamethrin and chlorpyriphos-ethyl of 13 populations of Typhlodomus pyri collected in vineyards in the Midi-Pyrénées region of France was demonstrated under laboratory conditions. The corrected mortality ranged from low to medium in all but one population, which was very susceptible to deltamethrin. This reduced toxicity of deltamethrin and chlorpyriphos-ethyl on the tested T. pyri populations would allow them to play an important role in IPM grapevines in the Midi-Pyrénées region, especially for the control of spider mites. There was no evidence of cross-resistance between deltamethrin and chlorpyriphos-ethyl.