The housefly (Musca domestica) is a common and important medical insect that can transfer over a hundred pathogens. Thus, there is a crucial need for effective strategies with biocompatibility properties to be considered in eliminating the widespread of this insect. Green-manufactured Zinc oxide nanoparticles ZnONPs and iron oxide nanoparticles (α-Fe₂O₃NPs) have been highlighted as biocompatible and eco-friendly choices to counteract the threat of insecticidal-resistant insects. Thus, the current study evaluates their potential by investigating their activity against 1st-instar larvae of houseflies. ZnONPs and α-Fe₂O₃NPs were synthesised using Piper nigrum fruit extract as a reducing and capping agent. The nanoparticles were characterised using an ultraviolet-visible spectrophotometer (UV-vis), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscope (SEM) measurements. The study explored the impacts of various concentrations of ZnONPs and α-Fe₂O₃NPs using a feeding assay of 1st-instar larvae and investigated the mortality and morphological changes in larvae, pupae, and emerging adults. Biogenic nanoparticles had a sub-spherical shape with a size of 20-30 and 30-40 nm for ZnONPs and α-Fe₂O₃NPs, respectively. The nanoparticles have caused obvious morphological abnormalities in the larvae, pupae, and adult emerging. The LC50 values of ZnONPs, α-Fe₂O₃NPs, and Piper nigrum fruit extract were 2, 1.2, and 75 mg/g, respectively. ZnONPs and α-Fe₂O₃NPs may accord to reducing the attempts, risk indications, and economic amounts raised from applying chemical insecticides. Thus, insect administration using nanoparticles could unfold deep, advanced sides.