DERMACENTOR ALBIPICTUS - WINTER OR MOOSE TICK

Considerable importance is attached to ticks as they are known to be the carriers of several diseases to man and to wild and domestic animals.  Most of the 29 species of ticks which had been recorded in Canada by 1956 are parasites of wild mammals and birds.  Man and domestic animals, however, frequently serve as hosts to several species.

At least nine species of ticks have been recorded from wildlife in Ontario and no doubt with further research other species will be found.  In Canada, the winter or moose tick, Dermacentor albipictus, is the species most commonly reported from wildlife.  It has been reported from caribou, wapiti (elk), mule deer, white-tailed deer, moose, bison, coyote and bear.

In Ontario D. albipictus is most frequently seen on moose.  It is present on moose, often in large numbers, from late fall to early spring.  Over 13,000 ticks have been recovered from a heavily infested moose, collected in the Chapleau Crown Game Preserve during March (Addison, Johnson and Fyvie, 1979).

Ticks mature and mate on moose during the winter.  In the spring the fertilized females drop to the ground where they lay their eggs amongst forest debris.  The eggs hatch after a period of approximately six weeks.  The larval or seed ticks that emerge from the eggs remain dormant throughout the summer.  Seed ticks become active in cool autumn weather and crawl up onto vegetation from which they are brushed onto passing hosts.  They attach to the body of the host and over a period of one or two months develop into nymphs and then into adult ticks.  During each of these three stages of development, the ticks extract a meal of blood from the host.  The adult female ticks, because of their large size, remove considerably more blood than the adult males, nymphs and seed ticks.

Adult winter ticks are large, reddish-brown to grayish-brown in colour and easy to see.  If a moose, heavily infested with ticks, is found dead the cause of death is often attributed to the presence of the ticks without consideration of other mortality factors.  Although more extensive study of other species of ticks suggests that D. albipictus may be a serious pathogen, there is little evidence to indicate that D. albipictus can be the sole cause of death of moose.

Selected Reference:

Addison, E.M., F.J. Johnson and A. Fyvie. 1979. Dermacentor albipictus on moose (Alces alces) in Ontario.  J. Wildl.  Dis. 15: (in press).