E-Fauna BC: Electronic Atlas of the Wildlife of British Columbia

Ixodes pacificus Cooley and Kohls, 1943
Western Black-Legged Tick
Family: Ixodidae

Photo of species

© Paul Dawson  Email the photographer   (Photo ID #123535)

E-Fauna BC Static Map
Distribution of Ixodes pacificus in British Columbia
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This species is found throughout western North America and in Canada is found only in British Columbia: it was first reported in Canada by Gregson (Lindquist 2016).

Morshed at al. report it from both BC and Alberta (Morshed et al. 2005). This requires clarification.

Hosts are reported as deer, dogs, cats and sheep (Lindquist et al 2016). This species will bite humans and is known to carry Borrelia burdorferi, the bacteria that causes Lyme Disease (Lindquist et al. 2016).

Biological information presented below is taken from Gregson 1956.

Species Information

Gregson (1956) describes this genus as follows: “Inornate ticks lacking eyes and festoons. Anal grooves embracing anus anteriorly. Palpi variable in form. Coxae about equal in size; spurs variable or absent. Males with seven non-salient ventral plates.” According to Higgins (1999), this species is a very tiny tick, with a red-brown body and black legs. Females have a long hypostome, which makes them hard to remove once attached (Gregson 1956). Gregson (1956) also says: “Ungorged females ...are easily separated from other species by their red-brown bodies and black legs, capitulum, and scutum. Upon feeding, their integument assumes a dull gray texture. The males are black, and about half the size of the unfed female.”


Species Biology

Gregson (1956) reports this as a short-lived species, and says larvae and nymphs have been demonstrated to feed on lizards; adults attach to deer, dogs, cats, sheep and humans. He indicates that: “the main season of adult activity for this species is from early fall till late spring... As a rule they are absent during the dry summer period.” This species is a principal vector of the Lyme Disease bacterium, Borrelia burdorferi and is also known to carry Babesia microti (Public Health Agency of Canada 2009).

Source: Gregson, John D. 1956. The Ixodoideae of Canada. Canada Deapartment of Agriculture, Ottawa


Gregson (1956) reports that “the habitat for this species is typified by damp, sunny, rocky slopes supporting such vegetation as Sedum and Mimulus spp., Cryptogramma acrostichoides (rock brake fern), Spiraea spp., and Arbutus menziesii.” It quests on vegetation (Easton and Goulding 1974).


Global Range

Dennis et al. (1998) describe this species distribution in the US: “... established populations of I. pacificus were found in 90 counties in 5 western states.”
Range in Canada and BC

According to Higgins (1999), in 1956 Gregson conducted a survey for this species in BC, and reported it as localized on the Pacific Coast, along the Fraser Valley to Boston Bar (e.g. along the Malahat, West Vancouver, Harrison Bay near Aggasiz, and Cultus Lakes), but in 1997 it was reported by the British Columbia Centre for Disease Control from the Cranbrook and Creston areas, with one solitary adult reported from Prince George. Collections from the Canadian National Collection now show the species has been found in the following locations: Abbotsford, Agassiz, Alex Lodge, Bear Mountain, Birken, Boston Bar, Brocklehurst, Burnaby, Chemainus, Cowichan, Cultus Lake, Duncan, East Sooke, Fisherman's Cover, Finlayson Arm, Gleneagles, Goldstream Provincial Park, Hardy Island, Hope, Kamloops, Kawkawa Lake, Nanaimo, North Vancouver, Pemberton, South Pender Island, Stump Lake, Texada Island, Vancouver, Victoria, and Whitecliff. Gregson (1956) reports this species as prevalent in heavily populated areas close to Vancouver and Victoria.

Status Information

Origin StatusProvincial StatusBC List
(Red Blue List)
BC Ministry of Environment: BC Species and Ecosystems Explorer--the authoritative source for conservation information in British Columbia.

Additional Notes

Morshed et al. (2005) report collections of Ixodes pacificus from birds in British Columbia and Alberta.

Additional Photo Sources

Species References

Gregson, John D. 1956. The Ixodoidae of Canada. Canada Department of Agricluture, Ottawa.

Lindquist, Evert E., Terry D. Galloway, Harvey Artsob, L. Robbin Lindsay, Michael Brebot, Heidi Wood and Richard. G. Robbins. 2016. A Handbook to the Ticks of Canada (Ixodida: Ixodidae, Argasidae Biological Survey of Canada, Ottawa

Morshed, Muhammad G., John D. Scott, Keerthi Fernando, Lorenza Beati, Daniel F. Mazerolle, Glenna Geddes, and Lance A. Durden. 2005. Migratory songbirds disperse ticks across Canada, and first isolation of the Lyme Disease spirochete, Borrelia burgdorferi from the avian tick, Ixodes auritulus. Journal of Parasitology 91 (4): 780–790.

General References

Recommended citation: Author, Date. Page title. In Klinkenberg, Brian. (Editor) 2021. E-Fauna BC: Electronic Atlas of the Fauna of British Columbia [efauna.bc.ca]. Lab for Advanced Spatial Analysis, Department of Geography, University of British Columbia, Vancouver. [Accessed: 2024-05-24 9:42:57 AM]
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