Sarcophaga Bullata - Feeding Habits

Feeding Habits

Adults of the family Sarcophagidae do not feed exclusively on carrion, despite the weighty implications of the name "flesh flies;" in fact, adult flies are frequently discovered feeding on sweet substances, such as sap and flower nectar. The flesh-eating character of the family refers primarily to sarcophagid maggots, which feed predominantly on carrion, exposed meat, and excrement. Sarcophaga bullata, in addition to all species of the family Sarcophagidae, may be considered "specialized flies," a term coined by Baker and Baker to describe flies that feed on carrion and dung. Specialized flies have been proven capable of detecting and selectively favoring plant nectars with high amino acid concentrations. Extensive research has suggested that S. bullata females in particular favor amino acid-containing nectars as opposed to strictly sugary nectars, perhaps to secure healthy levels of protein for successful reproduction.

Adult flesh flies are attracted to animal remains in both early and late decomposition stages, and have been known to fly through even the most extreme weather conditions to reach carrion. Though adult flies of the family Calliphoridae typically arrive on human remains before those of Sarcophagidae, sarcophagid adults are unhindered by nearly all climatic conditions and may reach the carrion first during particularly stormy weather. Rather than laying eggs, S. bullata females retain fertilized eggs internally until they develop into first-instar larvae, which are then deposited directly onto carrion. As sarcophagid larvae are larger than those of most other colonizing flies, they often present significant larval competition for other species. Though sarcophagid larvae have been attributed to causing myiasis, a condition in which maggots feed on the tissue of a living human or animal, they are most commonly discovered feeding on animal remains. In the southeastern United States, species of the genus Sarcophaga are the principal flies found during the warm summer months on bodies located indoors, as females frequently enter dwellings to deposit its larvae.

In terms of relevance to decomposing tissue analysis, forensic entomologists must disregard an egg development time period in post-mortem interval (PMI) calculations, as S. bullata and other sarcophagids deposit live larvae on carrion as opposed to eggs. For the same reason, fly egg masses discovered on human remains can be automatically ruled-out as belonging to sarcophagid flies.