Forensic entomology although not a commonly used discipline in the forensic sciences, does have its niche and when used by investigators is respected in crinimolegal investigations (Greenberg and Kunich, 2005). With many species of forensically significant insects being regionally specific, it is often difficult for forensic entomologists to as confidently translate regionally specific studies across drastically differing geographic regions (Brundage, et al., 2011). The purpose of this study is to help create a better temporal and geographic distributional understanding of the blow fly species present in Los Angeles County, California, United States. Twenty-five locations from four ecoregions (coastal mountains, urban, interior mountains, and desert) were regularly surveyed using baited traps for forensically significant blow flies throughout Los Angeles County from July, 2017 through January, 2018. In total 10,875 arthropod specimens were collected, of which 4,933 were the target family Calliphoridae. Six genera and twelve forensically significant species were recorded from the county during this time period. In addition to the current survey, all specimens from the Los Angeles Museum of Natural History and from select literature were included revealing an additional three species not collected during this current survey. Chrysomya rufifacies and Lucilia sericata comprised most the specimens recorded [collectively 87.9% (61.3% and 26.6% respectively)]. Several species define two ecoregions, Lucilia cuprina was only recorded below 1,000 feet elevation in urban disturbed environments, and Calliphora livida and Calliphora vomitoria define the San Gabriel Mountains having only been found there above about 4,000 feet elevation. Temporally, with Los Angeles having a rather Mediterranean climate year-round it is not surprising that most species have wide temporal distributions with only Calliphora terraenovae significantly restricted to only May-June. In summary, summer was the most species rich season with all 15 species recorded, and the San Gabriel Mountains had the highest diversity with 13 of the 15 species occurring there.