Phormia

Phormia is a genus of blow flies in the family Calliphoridae. It comprises several species, the most well known of which is Phormia regina, commonly called the black blow fly. Members of this genus are small to medium-sized flies that are often associated with decomposing animal matter and are widespread in temperate regions.

Phormia regina, the best-documented species in the genus, is frequently encountered on carrion and animal remains. Adult flies are typically dark in coloration with a metallic sheen that can appear blue-black or greenish depending on light. They resemble other calliphorid flies, but may be distinguished by specific morphological features used by taxonomists and forensic entomologists.

The life cycle of Phormia species begins when eggs are laid on exposed carrion or wounds. The eggs hatch into larvae (maggots) that feed on decomposing tissue through several instars before entering the pupal stage and later emerging as adults. Development is highly temperature dependent, with the duration from egg to adult ranging from about two weeks to a month or more under natural conditions. Adults feed on nectar, moisture, and sometimes decaying matter.

Geographic distribution for Phormia regina shows a strong association with the Nearctic region, particularly North America, with occurrences reported in parts of Central and South America. The genus as a whole is best studied in forensic and ecological contexts in these regions, where species play roles in decomposition and nutrient cycling.

Forensic entomology recognizes Phormia regina as a key indicator species for estimating postmortem intervals in suitable climates. Identification relies on careful examination of adult morphology, larval characteristics, and increasingly DNA-based methods to distinguish closely related species.