<p><strong>Background.</strong> <em>Tetranychus urticae</em> Koch is a species of phytophagous mites with wide importance in the production of fruit and horticultural crops, as well as ornamental species. A strategy that can contribute successfully to the management of mites is the use of metallic phytonanoparticles (NPs) synthesized from plant extracts. <strong>Objective.</strong> To evaluate the acaricidal effect of chipilín (<em>Crotalaria longirostrata</em>) bimetallic NPs on <em>T. urticae</em> and its phytotoxic activity in eggplants (<em>Solanum melongena</em>). <strong>Methodology.</strong> To evaluate mortality, groups of mites were exposed to eggplant leaf discs treated with (NPs), and mortality was recorded at 48 and 96 h. To evaluate the quantum efficiency of chlorophyll, photochemical parameters were measured in the leaves of eggplant plants 40 days after emergence. <strong>Results</strong>. The NPs of Cu-Zn at concentrations of 100 and 150 ppm caused more than 70% mortality in <em>T. urticae</em> adults, whereas the NPs of Ag-Zn at concentrations of 50, 100 and 150 ppm caused more than 80% mortality in <em>T. urticae</em> eggs. The application of bimetallic NPs from <em>C. longirostrata</em> did not cause toxic stress in eggplant plants, as the quantum efficiency of photosystem II was not affected. <strong>Implication.</strong> The use of <em>C. longirostrata</em> bimetallic NPs may be an alternative to the chemical acaricides for the management of <em>T. urticae</em>. <strong>Conclusion.</strong> The NPs of Cu-Zn and NPs of Ag-Zn produce more than 70% mortality in <em>T. urticae</em> adults and eggs.</p>