Lipoptena depressa

Distinguished from ticks (Ixodidae) by having six legs rather than eight. Differentiated from other deer ked species by geographic range: L. depressa occurs in western North America, while L. cervi is found in the northeastern US and eastern Canada, and L. mazamae in the southeastern US and Central/South America. After wing shedding, may be confused with L. cervi; geographic location is the primary distinguishing feature. The winged adult form could potentially be confused with other Hippoboscidae, but host association and range help confirm identity.

Associated with deer habitats in western North America, including regions containing the Rocky Mountains. Adults are found on host animals; pre-pupal larvae and pupae occur in ground substrate where they fall from hosts.

Western United States (Washington, Oregon, California, Idaho, Montana, South Dakota, Colorado, Utah) and Alberta, Canada. Native to this region.

Adult emergence and host-seeking activity has been observed in fall (November-December in some regions), though specific timing may vary by location and climate. Mass emergence events can occur over concentrated periods.

Blood-feeding ectoparasite specialized on deer. Adults take multiple small blood meals from the host rather than single large meals.

• Odocoileus hemionus - primary hostmule deer
• Odocoileus virginianus - primary hostwhite-tailed deer
• Odocoileus hemionus columbianus - primary hostColumbian black-tailed deer

Females are ovoviviparous, producing one larva at a time and retaining it internally through all three instars. The fully developed third-instar larva is born alive (as a pre-pupa), immediately drops from the host, buries itself in the ground, and pupates. Adults emerge from pupae with wings, fly to locate a host (limited to approximately 50 meters), shed wings upon host contact, and remain on the host for reproduction and feeding. Lifespan on host estimated at 8-13 months, with females producing 4-7 larvae during this period.

Adults exhibit limited flight capability (approximately 50 meters), making host location dependent on deer density and distribution. Upon finding a host, adults immediately shed wings and become permanently associated with that host. They are highly mobile on the host, dodging grooming attempts and using flattened body shape and clawed legs to slip between hairs and grip hide. Wingless adults remain capable of rapid movement. Do not voluntarily leave hosts except when females give birth to larvae.

Ectoparasite of deer with potential role in disease transmission dynamics among deer populations. Heavy infestations (documented at over 2000 flies per host) can cause host discomfort and calcaneus hemorrhages in white-tailed deer, potentially leading to secondary disease or death. Associated with bacterial symbionts including Corynebacterium lipoptenae.

Occasionally misidentified as deer ticks, causing concern among hunters and hikers. Rarely bites humans; documented human bites are few and typically associated with handling infested deer carcasses. Not known to vector human diseases. Can be a nuisance to hunters and deer processors during fall hunting season. Standard insect repellents (DEET, picaridin, etc.) have been shown ineffective against deer keds in studies of related species; permethrin-treated clothing may increase mortality upon contact.

• Lipoptena cerviSimilar winged-then-wingless life history and tick-like appearance after host colonization; distinguished by geographic range (northeastern US and eastern Canada vs. western range of L. depressa) and by L. cervi being introduced from Europe
• Lipoptena mazamaeSimilar morphology and biology; distinguished by geographic range (southeastern US, Central and South America)
• Ixodes scapularis (deer tick)Frequently misidentified due to similar size, flattened shape, and blood-feeding parasitism on deer; distinguished by having 6 legs (insect) vs. 8 legs (arachnid), and by L. depressa being more host-specific and mobile

Commonly misidentified as ticks due to wingless, flattened appearance on hosts. Despite being blood-feeding parasites, they are not known to transmit diseases to humans, contrary to assumptions based on their similarity to ticks. Reports of increasing bites on humans in some regions may refer to the introduced L. cervi rather than the native L. depressa.

• ectoparasite
• deer parasite
• louse fly
• wing shedding
• ovoviviparity
• western North America
• Hippoboscidae
• blood feeder

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Bug Eric: Louse Flies? Are You "Ked"-ing Me?
• Meet the Deer Ked: The Fly That Makes Life Tough for Hunters and Hikers
• Remarkable Bat Discoveries from the ZooKeys Archives | Blog
• A New Bacterium, Corynebacterium lipoptenae, Associated with the Louse Fly, Lipoptena depressa Say
• 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))