The impact of relative humidity on Phormia regina (Diptera: Calliphoridae) oviposition

Forensic entomology employs the study of insect development in specific climates to estimate the postmortem interval. However, variations in the pre-appearance interval (PAI), which refers to the time between death and insect infestation, can significantly impact the accuracy of postmortem interval determinations. In cases where insect evidence is absent, it is uncertain whether the PAI was not overcome or if environmental conditions prevented oviposition. Furthermore, the influence of humidity on blow fly oviposition is not well understood. We studied the oviposition timing and behavior of the black blow fly, Phormia regina (Diptera: Calliphoridae), under different humidity conditions. Our results showed that flies laid eggs at similar times across humidity levels, but lab-adapted flies were less affected by humidity extremes than wild-caught flies. Female flies exposed to low humidity as larvae laid most eggs in the evening, implying maternal influence on egg-laying behavior based on larval environment.