This article presents the methodology and results of research, in which the authors’ goals were to establish stage transition distributions with confidence intervals across all life stages, egg to adult, and multiple temperatures for L. sericata and Phomia regina; the research has implications for forensic science and practicing coroners and medical examiners in the field.
Blow fly development rates have become a key factor in estimating the postmortem interval where blow flies are among the first decomposers to occur on a body. Because the use of blow fly development requires short time durations and high accuracy, stage transition distributions are essential for proper development modeling. However, detailed examinations of stage transitions are not available for any blow fly species. Consequently, the authors examined this issue in two blow fly species: Lucilia sericata and Phormia regina. Transitions for all life stages across all measured temperatures were normally distributed. Use of probit analysis allowed determination of 50 percent transition points and associated measures of variation (i.e., standard errors). The greatest variation was noted for the L2-L3, L3-L3m, and L3m-P stage transitions. These results invalidate the notion that largest maggots should be preferentially collected for determining current maggot population stage, and further call into question the relationship between intrinsic variation and potential geographic variation in development rates. Publisher Abstract Provided