Cephenemyia jellisoni

Larvae possess a distinctive cephalopharyngeal apparatus and tracheary system visible in first instars; puparia are dark, hardened cases found on soil surface after larvae exit host nostrils. Adult females lack functional mouthparts. Distinguished from C. apicata by larval morphology and by attacking behavior: C. jellisoni attacks from a blind spot below the deer's nose with inaudible hovering flight, while C. apicata lands visibly on or near deer.

Associated with deer host range; adult males aggregate at upper hillside and summit stands of Castanopsis and Quercus rising 2–10 feet above surrounding scrub vegetation.

Northwestern North America; recorded from southern Vancouver Island, British Columbia, California, and broadly across the Pacific Northwest.

Adult activity begins at 20°C air temperature and ends soon after mid-day during active seasons. First instar larvae undergo 6–8 month development during fall/winter months, ensuring adult eclosion during favorable conditions.

• Odocoileus hemionus columbianus (Columbian black-tailed deer) - primary hostLarvae develop in nasopharynx and retropharyngeal recesses
• Odocoileus virginianus (white-tailed deer) - hostDocumented host per distributional records
• Alces americana (American moose) - hostDocumented host per distributional records
• Cervus canadensis (elk/wapiti) - hostDocumented host per distributional records

Females are larviparous, depositing first instar larvae directly into host nostrils. First instars initially occupy the nasopharynx, then migrate to retropharyngeal recesses for second and third instar development. Mature third instars exit through nostrils and pupate in soil. Puparial stage precedes adult eclosion. Total first instar development spans 6–8 months during fall/winter.

Females employ covert, inaudible hovering 'stalking' flight during attack, approaching from a blind spot in front of and below the deer's nose. Larviposition triggers immediate host reactions: head jerking, sneezing, head shaking, and nose lowering to ground. Males aggregate at specific elevated sites, engage in intraspecific and intrageneric chasing, and show site fidelity throughout daily activity periods. Mating occurs in flight with pairs dropping in tandem to vegetation.

Internal parasite of cervid hosts; population dynamics linked to deer density and distribution.

• Cephenemyia apicataLarvae were historically misidentified between these species; C. apicata attacks from visible perched positions rather than covert hovering, and first instars undergo an obligate lung phase in bronchi before molting—absent in C. jellisoni
• Cephenemyia phobiferaShares northeastern distribution and Odocoileus virginianus host; distinguished by geographic range and specific larval morphology
• Cephenemyia trompeNorthern distribution with Rangifer hosts; overlaps with C. jellisoni in O. hemionus parasitism but differs in primary host spectrum

• parasite
• deer parasite
• Oestridae
• myiasis
• larviparous
• cervid host
• nasal bot fly
• Pacific Northwest
• covert attacking behavior
• site fidelity

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• Wednesday “What the heck?” | Beetles In The Bush
• Corrected misidentification of first instars of the bot flies Cephenemyia apicata and C . jellisoni , with a review of the biology and life history of both species
• NOTES ON THE LIFE HISTORY AND MORPHOLOGY OF CEPHENEMYIA JELLISONI TOWNSEND AND LIPOPTENA DEPRESSA SAY, TWO DIPTEROUS PARASITES OF THE COLUMBIAN BLACK-TAILED DEER (ODOCOILEUS HEMIONUS COLUMBIANUS (RICHARDSON))
• The behavior of nose bot flies (Cephenemyia apicata and C. jellisoni) when attacking black-tailed deer (Odocoileus hemionus columbianus) and the resulting reactions of the deer
• Field Behavior of Adult Cephenemyia (Diptera: Oestridae),
• THE NEARCTIC SPECIES OF THE GENUS CEPHENEMYIA (DIPTERA, OESTRIDAE)