Pathogenicity of larval Protocalliphora (Diptera: Calliphoridae) parasitizing nestling birds

Controlled tests showed that feeding by larvae of several species of Protocalliphora lowered haematocrit and haemoglobin levels of nestling magpies and bank swallows. Subsequent studies showed that natural populations of nestling magpies and Bank Swallows infested by P. asiovora and P. chrysorrhoea, respectively, experienced significantly reduced blood levels at the P0.05 and P0.01 levels except in the youngest nestlings. Despite the presumed heavy blood loss, most nestlings are not killed by larvae of Protocalliphora. Studies of natural populations of Protocalliphora in 48 species of birds indicate that the larval populations are usually too small to kill or seriously injure most nestlings.