Melon fruit fly (Bactrocera cucurbitae (Coquillett)) severely constrains bitter gourd (Momordica charantia L.). We developed a Chromolaena odorata (L.) R.M.King & H.Rob. extract-mediated silver nanoparticle spray (CO-AgNPs) and evaluated its greenhouse-to-field efficacy together with residue dissipation and crop safety. CO-AgNPs were applied as full-cover foliar sprays in randomized complete block designs, comparing three rates with CO, AgNO₃, and a protein-bait benchmark (Sofri Protein 10DD; 0.02% spinosad). Under high pest pressure, CO-AgNPs reduced fruit infestation to 25.21-19.61% in greenhouse cages (control 78.01%) and to 28.06-22.55% in on-farm field plots (control 65.13%), comparable to Sofri (20.08% and 24.36%, respectively). Total silver residues (acid digestion followed by inductively coupled plasma-mass spectrometry) were higher in peel than in pulp and declined after the last spray; pulp concentrations remained low, and soil silver showed no increasing trend. Together, these findings support a conservative, provisional pre-harvest interval of 7 days for the tested program. Chromolaena odorata-derived silver nanoparticles (CO-AgNPs) were non-phytotoxic at the recommended rate based on the chlorophyll meter index (SPAD), the maximum quantum efficiency of photosystem II (Fv/Fm), and visual injury assessment. These results indicate CO-AgNPs as a promising foliar complement for residue-aware integrated pest management of melon fruit fly on bitter gourd.