Effects of Antibiotic Use on Larval House Fly Development

House flies (Musca domestica L.) are persistent pests in dairy operations, thriving in manure and other waste products that also may contain antibiotic residues. To evaluate the effect of antibiotic residues on house fly development, laboratory-reared flies with no prior antibiotic exposure and wild flies collected from a dairy were raised in tetracycline- and enrofloxacin-infused growth media. Laboratory colony flies showed reduced larval weight, while wild-caught flies were less affected, suggesting prior environmental exposure may increase tolerance to chemical stressors. These findings suggest that antibiotics in manure may act as chronic chemical stressors, driving future tolerance to insecticides in adult house flies.