If you go out in the woods today ...
There are 34 species of ticks recorded for Canada, but only 11 of these are found in the prairie provinces. Most of these species are quite host specific, found mainly on sharp-tailed grouse (Haemaphysalis chordeilis (Packard)), rabbits (Haemaphysalis leporis-palustris (Packard)), ground squirrels (Ixodes sculptus (Neumann) and Ixodes kingi (Bishopp)), groundhogs (Ixodes cookei (Packard)), or small rodents (Ixodes angustus (Neumann) and Ixodes muris (Bishopp & Smith)). People rarely encounter these specialists on their casual hikes across the prairie landscape, but there are a few others that are cause for concern.
Two species of wood ticks are the ticks most frequently encountered on ourselves and on our dogs and cats in the prairie provinces. The American dog tick or wood tick, Dermacentor variabilis (Say) is an eastern species, known in Canada from Nova Scotia to south central Saskatchewan. There is lots of anecdotal evidence to support the notion that this tick has expanded its range in the last few decades. It is now quite common in the upper Interlake region of Manitoba, and in the Saskatoon area. The adults of this species are generally a dark, reddish brown, with distinct white markings on the back. Males have a plate, the scutum, which covers the entire back, while in females, the scutum covers only the anterior part of the back. It is the scutum which bears the white markings, so you can tell the male tick from the female tick at a glance. The Rocky Mountain wood tick, Dermacentor andersoni (Stiles), is found in western Canada from southwestern Saskatchewan, across southern Alberta and into British Columbia. To the unaided eye, the adults of this species are nearly indistinguishable from the American dog tick.
Although the timing of the life cycles of these two species is rather different, they both take about two years to complete a generation, and it is the adults that we most often encounter. The juvenile stages, the six-legged larvae and the eight-legged nymph, most often feed on small mammals, such as mice and voles. The adults become active in the spring, and you can sometimes find them on the vegetation on warm days even when there is a bit of snow left in the trees.
Questing adults crawl up onto the low vegetation where they wait for a suitable host to come by. They have specialized sensory organs on their front legs, and when they detect a host, they wave these legs about and snag the hair or clothing of their prey at the appropriate moment. Adult ticks are not all that fussy, and they feed on a variety of medium-sized to large mammals, including skunks, coyotes, badgers, bears, deer, dogs, cats and humans.
They do not jump, and I have never known wood ticks to climb up into oak trees to pounce on unsuspecting prairie gardeners as they walk below. However, they are very good at what they do, and they can get beneath your clothing to find a suitable place to attach and begin feeding without your knowing. You may not find the tick until later when you take a shower, or when someone points out to you that you have a tick on your back. This is probably what most people find so creepy about wood ticks.
Both males and females require blood, and blood is all they ever feed on. Males generally feed for only a short time before they wander off in search of a female. Females, on the other hand, may remain attached, feeding for several days, during which they fill with blood, reaching the size of a small grape (see photo, page 79). Mating occurs on the host, as the female continues to feed, and once mated and fully engorged, the female will drop to the ground, find a sheltered location, and lay 3,000 eggs or more.
In the last 10 to 15 years, another tick has drawn a lot of attention, and people have been quite concerned about the possibilities of acquiring Lyme Disease as a result of contact with this tick. The blacklegged tick or deer tick, Ixodes scapularis (Say), is one which feeds on a great variety of different hosts, including mammals and birds. In the prairies, it was first collected in Manitoba in 1989, and since then has been found throughout southern Manitoba. There are a few recorded sitings for southeastern Saskatchewan and southern Alberta. As far as we know, the blacklegged tick has not become established in the prairies. It seems that it disperses into central Canada from endemic areas of the United States on migrating birds. The critical thing to remember about the blacklegged tick is that they are active from early spring to late fall or even early winter. In the past, people have considered the tick season to be the spring and early summer months. With blacklegged ticks, it is important to be vigilant until temperatures drop to well below freezing or until snow covers the ground.
Also of great concern with blacklegged ticks is that they are dispersing from areas where the bacteria that causes Lyme Disease is present in the population. Extensive surveillance for blacklegged ticks has been conducted in Manitoba and Saskatchewan. Of about 290 blacklegged ricks collected in Manitoba since 1996, approximately 10% have tested positive for the bacteria that causes Lyme Disease. Although blacklegged ticks have not become permanently established in the prairies, there is a small risk of picking up this tick, and even for becoming infected with the bacteria.
There is no reason to be alarmed by the presence of ticks in the area that you have selected for your hike. For many people, they are an unpleasant component of our environment, and there is the risk of becoming infected with pathogens that may cause Lyme Disease, or in the west, Rocky Mountain Spotted Fever. The best defence against ticks is early detection. You should always examine yourself, your children and your pets carefully if you have been in the field where there is a chance that you may have picked up ticks.
If you find a tick which is attached and has begun feeding, pull the tick out using slow, steady force. Do not yank the tick out, twist it out, burn it out, or smother it with grease or paste. Once the tick has been removed, apply an antiseptic to the bite, and watch the area carefully. It is not unusual for people to have a localized reaction to tick bites, but if you notice that there is an unusual amount of swelling, soreness or redness around the bite, you should see your physician. You should also consult with literature published by your local health authorities on the various pathogens that are transmitted by ticks in your area. Know the symptoms of these tick-borne diseases so that you may get appropriate diagnosis and medical attention as soon as possible.
When you venture out into the field to observe our native flora, read up on the plant species that you might expect and carry a good field guide with you. Don't let the presence of ticks spoil your outing. Arm yourself with knowledge about ticks, and how best to deal with them when they find you. Ticks are marvellously adapted blood-sucking parasites and we should appreciate them as part of our natural landscape.
Galloway, T.D. 1989. Lyme Disease vector, Ixodes dammini, identified in Manitoba. Canadian Diseases Weekly Report, 15-27: 85.
Galloway, T.D., L.R. Lindsay, A. Dibernardo & H. Artsob. 2001. Surveillance for blacklegged ticks, Ixodes scapularis (Acari: Ixodidae), in Manitoba, a non-endemic area of central Canada. Proceedings of the Northwest Conference on Diseases in Nature Communicable to Man, Winnipeg, Manitoba, 29 July to 1 August, 2001. p.1.
Lindsay, L.R., H. Artsob, T.D. Galloway & G. Horsman. 1999. Vector of Lyme Borreliosis, Ixodes scapularis, identified in Saskatchewan. Canadian Communicable Diseases Report, 25-9: 1-3.
Scott, J.D., K. Fernando, S.N. Banerjee, L.A. Durden, S.K. Byrne, M. Banerjee, R.B. Mann & M.G. Morshad. 2001. Birds disperse ixodid (Acari: Ixodidae) and Borrelia burgdorferi--infected ticks in Canada. Journal of Medical Entomology, 38: 493-500.
Don't like squishing wood ticks? Drop them into undiluted dishwashing detergent--it does the job quickly!
Itchy wood tick bites? To soothe, rub them with fresh aloe vera juice, the same as you would with a burn.
Dr. Terry, Galloway is a professor with the Department of Entomology, Faculty of Agricultural and Food Sciences, at the University of Manitoba.