Larvae of Philornis carinatus are subcutaneous hematophagous feeders recorded from Costa Rica. P. carinatus parasitism can lead to reduced nestling mass, as well as reduced development of wing chords and tarsi in nestling house wrens (Young, 1993).
Unlike Philornis downsi, larvae of P. deceptiva are subcutaneous hematophagous feeders that burrow into the host's integument. They form individual cysts beneath the skin in which they feed on blood and body tissues of the nestling, and can breathe through a small aperture in the host's integument (discussed in Dudaniec et al, 2006). Arendt (1985a &b), found that 97% of Pearly-eyed Thrasher nestlings (Margarops fuscatus) in Puerto Rico were infested with P. deceptiva larvae. Parasitism caused delayed nestling growth and development, and was responsible for 47% of nestling deaths. Parasitism was also responsible for loss of red blood cells, connective tissue and tissue fluids (Uhazy and Arendt, 1986).
Larvae of Philornis seguyi are subcutaneous hematophagous feeders, and parasitise a variety of host species. Larval infestation was found to induce nestling mortality. Has been recorded in Argentina (Couri et al, 2005)