The temperature dependent development rates of blow flies allow blow flies to be used as biological clocks in forensic death investigations. However, the upper thermal limits of adult survival and oviposition, both required for producing larvae, remains largely unknown. Therefore, in this study we examined the impact of a range of temperatures between 37 °C and 44 °C on the likelihood of survival and egg-laying behavior of two species of medicolegal forensic importance, Lucilia sericata (Meigen) and Phormia regina (Meigen) (Diptera: Calliphoridae). To quantify the upper temperature limits of survival, adult fly colonies were exposed to 37 °C, 41 °C, 42 °C, 43 °C, and 44 °C for 24 h. Similarly for oviposition trials, adults of both species were exposed to 40 °C, 42 °C, and 43 °C with P. regina oviposition also observed at 41 °C. Trials lasted for 24 h with oviposition substrate replenished at the 12 h mark. A yes/no determination on egg deposition was made, eggs were counted, and a yes/no determination was made on egg hatch. Survival did not differ by species (p = 0.096). Overall, survival decreased with increasing temperatures, with ~100% at 37 °C, ~50% at 41 °C, ~37% at 42 °C, ~15% at 43 °C and 0% at 44 °C. Lucilia sericata laid eggs capable of hatch up to 43 °C, while Phormia regina egg-hatch was observed up to 41 °C. These results indicate a greater thermal tolerance of adult survival than for egg deposition and successful egg hatch, which supports previous experiments indicating blow flies stop laying eggs at sub-lethal temperatures. Furthermore, these data indicate that adult blow flies may find remains at or near time of death but may delay egg deposition until temperatures drop below an acceptable threshold.

A geometric morphometric analysis was performed on the right wing of adult Calliphora vicina (Robineau-Desvoidy) collected across 4 altitudinal levels in Sicily. The objective of this study was to assess differences in shape and centroid size (CS) between females and males and across elevations. The wings analyzed in this study were removed from adults of C. vicina collected with baited traps at 20, 700, 1,153, and 1,552; for this study, 19 landmarks were identified in each wing. The coordinates of the landmarks were aligned and superimposed to prevent variations due to position, orientation, and scale; they were then scaled to the same CS and recentered. CS and Procrustes differences were, respectively, used to assess variations in size and shape. Significant differences were observed in wing shape between males and females but not between all altitudinal levels. Female wings were found to be significantly larger than males (P < 0.01). Wings of flies collected at the highest altitudinal level resulted in significantly larger wings than those collected at lower altitudes (P < 0.001), with CS values ranging from 12.1 to 14.1. Variation in wing shape can impact thermal regulation, and therefore, oxygen content, temperature, atmospheric pressure, and solar radiation can have an effect on an insect’s body and activity levels. At high elevations and lower temperatures, larger wings could mean less energy expenditure when flying to increase body temperature.

Blow flies (Diptera: Calliphoridae) are among the first insects to arrive on a corpse, and so they are particularly important in forensic entomology. To use blow flies in forensic investigations, there must be information available on their species diversity, abundance, and distribution in the areas where investigations are conducted. Several factors can contribute to species distribution, and elevation is one of those factors. The purpose of this study was to document the distribution of Calliphoridae across four elevational gradients in Sicily and Ecuador, where little information is available. Baited traps were placed at elevations ranging from 20 m to 1552 m in Sicily (a major island and region of Italy and a distinct ecoregion) and 561 m to 3336 m in Ecuador. Species richness, relative abundance, and diversity were calculated, as well as the ratio of female to male blow flies and community assemblage. Twelve species were collected in Sicily, and seventeen species were collected in Ecuador. In Sicily, the most abundant species was Lucilia sericata (Meigen) (68.50% of the total capture), while in Ecuador, it was Compsomyiops verena (Walker) (51.67% of the total capture). In Sicily, significant differences were only observed in the relative abundance of L. sericata across elevations. In Ecuador, significant differences were observed in the relative abundance of Calliphora nigribasis (Macquart), Chrysomya albiceps (Wiedemann), C. verena, Hemilucilia semidiaphana (Rondani), Lucilia ibis (Shannon), L. purpurascens (Walker), and Paralucilia sp. across elevations. These data can help build a checklist of blow fly species in these two regions and can be instrumental in environmental and forensic investigations.