Physical Description

Type Information

Holotype for Philornis downsi Dodge & Aitken, 1968
Catalog Number: USNM
Collection: Smithsonian Institution, National Museum of Natural History, Department of Entomology
Sex/Stage: Male;
Preparation: Pinned
Collector(s): T. Aitken & W. Downs
Year Collected: 1957
Locality: Cunaripo R.c. school; Trinidad; B.W.I, Unknown, Trinidad and Tobago
  • Holotype: 1968. Journal of the Kansas Entomological Society. 41: 138.
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© Smithsonian Institution, National Museum of Natural History, Department of Entomology

Source: National Museum of Natural History Collections


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Philornis downsi

Philornis downsi is a species of fly (Diptera, Muscidae) that was first recorded in Trinidad and Brazil in the 1990s.[1] It has been accidentally introduced to the Galapagos Islands (Ecuador). Adult P. downsi feed on fruit. Eggs are laid in bird nests and hatch into parasitic larvae which reside in the nest material and emerge at night to feed both internally and externally on the blood and flesh of developing nestlings.[2] The parasite is causing significant mortality in Darwin's finch nestlings and threaten the survival of some rarer species such as the Mangrove Finch (Camarhynchus heliobates) and the Medium Tree Finch (C. pauper).[3]


  1. ^ Dudaniec RY, Fessl B & Kleindorfer S. (2007) Interannual and interspecific variation on intensity of the parasitic fly, Philornis downsi, in Darwin's finches. Biological Conservation, 139, 325-332.
  2. ^ O’Connor JA, Dudaniec RY, Kleindorfer S (2010) Parasite infestation in Galapagos birds: contrasting two elevational habitats between islands. Journal of Tropical Ecology. 26: 285-292. doi:10.1017/S0266467409990678
  3. ^ O’Connor JA, Sulloway FJ, Robertson J, Kleindorfer S (2010) Philornis downsi parasitism is the primary cause of nestling mortality in the critically endangered Darwin’s medium tree finch (Camarhynchus pauper). Biodiversity and Conservation. 19:853-866. doi:10.1007/s10531-009-9740-1
  • Dudaniec RY, Gardner M G, Donellan S & Kleindorfer S (2008) Genetic variation in the invasive avian parasite, Philornis downsi (Diptera, Muscidae) on the Galápagos archipelago. BMC Ecology, 8, 13.
  • Dudaniec RY, Hallas G & Kleindorfer S. (2005) Blood and intestinal parasitism in Darwin's finches: negative and positive findings. Acta Zoologica Sinica, 51, 507-512.
  • Dudaniec RY & Kleindorfer S (2006) The effects of the parasitic flies Philornis (Diptera, Muscidae) on birds. EMU, 106, 13-20.
  • Dudaniec R Y, Kleindorfer S & Fessl B (2006) Effects of the introduced ectoparasite Philornis downsi on haemoglobin level and nestling survival in Darwin's small ground finch (Geospiza fuliginosa). Austral Ecology, 31, 88-94.
  • Fessl B, Couri M. & Tebbich S. (2001) Philornis downsi Dodge & Aitken, new to the Galápagos Islands, (Diptera, Muscidae). Studia Dipterologica, 8, 317-322.
  • Fessl B, Kleindorfer S & Tebbich S. (2006a) An experimental study on the effects of an introduced parasite in Darwin's finches. Biological Conservation, 127, 55-61.
  • Fessl B, Sinclair BJ & Kleindorfer S (2006b) The life cycle of Philornis downsi (Diptera: Muscidae) parasitizing Darwin's finches and its impacts on nestling survival. Parasitology, 133, 739-747.
  • Huber S K (2008) Effects of the introduced parasite Philornis downsi on nestling growth and mortality in the medium ground finch (Geospiza fortis). Biological Conservation, 141, 601-609.
  • Huber SK, Owen JP, Koop, JAH, King MO, Grant PR, Grant BR, Clayton DH (2010) Ecoimmunity in Darwin’s Finches: Invasive Parasites Trigger Acquired Immunity in the Medium Ground Finch (Geospiza fortis). PLoS One. 5(1):e8605
  • O'Connor JA, Robertson, J, & Kleindorfer, S (2010) Video analysis of host-parasite interactions in Darwin's finch nests. Oryx, 44, 588-594.

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