Michael Diaz is a sophomore majoring in Biology at the California State University in Monterey Bay. This summer (2010) Michael participated in our Research Experience for Undergraduates (REU) program which is sponsored by the National Science Foundation. Michael investigated the relationship between blow fly (Diptera: Calliphoridae) larval size and time of dispersal from carrion. Michael determined that those initially dispersing from carrion are larger than those dispersing at a later time indicating that those colonizing late are penalized in their ability to gain weight (i.e., greater larval competition for limited resources). Consequently, less weight could translate into reduced ability to survive, mate, and reproduce. This information has forensic significance as larval size (i.e., length and weight) are often used to estimate time of colonization. Failure to recognize the phenotypic variation existing within a species could result in an over, or under, estimate of the time of colonization.