ISSN: 0022-1198
CODEN: JFSCA
Page Count: 6

Estimating Maggot Age from Weight Using Inverse Prediction
Wells, JD
NSF/STA Fellow, National Institute of Health,

LaMotte, LR
Professor and Head, Louisiana State University, LA

(Received 27 July 1994; accepted 28 October 1994)

Abstract

Forensic entomological evidence is most often used to estimate the postmortem interval (PMI). Satisfactory techniques have not been available to quantify the precision of such a PMI estimate. For Cochliomyia macellaria (F.) (Diptera: Calliphoridae), we describe construction of a confidence interval on age of a larva, given its weight. The method requires a controlled experiment by which weights of larvae are observed at ages spread over sufficient range to cover the time from egg hatch up to postfeeding stage. A statistical model relating distributions of weights to age is formulated and fit to these data. We assumed a simple model in which both means and variances of weight distributions are linearly interpolated between sampled ages. The weight of a larva of unknown age is then compared to the fitted model via inverse prediction to compute the confidence interval on age of the larva.

Keywords:
forensic science, forensic entomology, Cochliomyia macellaria, Calliphoridae, prediction statistics, postmortem interval, maggot growth rate

Paper ID: JFS13830J
DOI: 10.1520/JFS13830J
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