Blacklegged Ticks (Deer Tick, Bear Tick) - Tickborne Disease - Minnesota Dept. of Health

Ticks

In Minnesota, there are about a dozen different types of ticks. Not all of them spread disease. Three types that people may come across in Minnesota are the blacklegged tick (aka deer tick), the American dog tick (aka wood tick), and the lone star tick. The blacklegged tick causes by far the most tickborne disease in Minnesota. People in Minnesota are often bitten by American dog ticks but they rarely spread diseases. American dog ticks may spread Rocky Mountain spotted fever and tularemia. Lone star ticks are rarely found in Minnesota, but can spread diseases such as ehrlichiosis and tularemia.

Image showing the different appearences of different tick varieties.

The blacklegged tick, shown in the lower right, is much smaller than the American dog tick, shown in the upper right. The lone star tick is shown in the upper left of this photo and is a little smaller than the American dog tick but larger than the blacklegged tick

On this page:
Life Cycle
Habitat
Photos

Blacklegged Tick Life Cycle

Blacklegged ticks live for about two to three years. Most of their life is spent out in the environment rather than on a host or in a host’s nest. During their entire lifetime, they will only have up to three blood meals. The picture below shows that the life cycle begins when the female lays eggs. As the egg matures, it develops into a larva (right-middle), then a nymph (top-middle) and finally, an adult male or female (bottom-right).

Image of the lifecycle of a tick

In the spring of their first year, eggs hatch into larvae. Larvae prefer to feed on blood from small mammals, like mice and birds. Larvae have one feeding then molt into nymphs and rest until the next spring. During this first meal, the larva may pick up a disease agent (like the bacteria that causes Lyme disease) while feeding on a small mammal, such as a white-footed mouse.

Late in the spring of their second year, nymphs take their second feeding. Nymphs aren’t as picky with their choice of host and will feed on blood from small or large mammals, such as white-tailed deer or humans. At this time, if the nymph is infected with a disease agent then it could spread the disease agent to a human or animal that it feeds on.

In the fall of their second year, nymphs that have had a blood meal will molt into an adult male or female tick. Adults prefer to feed on large mammals, such as white-tailed deer or humans. The females find a host to feed, mate with an adult male tick, lay hundreds to thousands of eggs, and then die. The males attach to a host to find a female mate and then die. Some adults who do not feed or mate in the fall will survive through the winter and then come out to feed and/or mate the following spring. If there is little to no snow cover and temperatures rise above freezing, it is possible to find an active adult tick searching for a host on a warm winter day.

In Minnesota, adult ticks will usually emerge right after the snow melts and reach peak spring-time activity during the month of May. The adult ticks will typically stay active throughout June. Adults will also become active again in the fall, usually by the end of September and through October, until temperatures drop below freezing or snow covers the ground. Blacklegged tick nymphs start to become active in mid-May and reach peak activity at the end of May through the month of June. Nymph activity tapers off slowly, and they are much less active by the end of July. Larvae are typically most active in June.

Image of the the life sizes of a tick

This picture shows each of the life stages of the blacklegged tick: adult female, adult male, nymph, and larva. It also shows the relative sizes and patterns of the blacklegged tick, lone star tick, and American dog tick.

Feeding and blood meals

  • Blacklegged ticks feed on blood by inserting their mouth parts into the skin.
  • They are slow feeders and will usually feed for 3-5 days.
  • In order to spread disease to a human or animal, a tick needs to be infected with a disease agent and it needs to be attached to the host for a certain amount of time.
    • If the blacklegged tick is infected, it must be attached for 24-48 hours before it transmits Lyme disease.
    • Less common tickborne diseases, such as anaplasmosis, may take less time.
    • On average, about 1 in 3 adult blacklegged ticks and 1 in 5 blacklegged tick nymphs is infected with the bacteria that causes Lyme disease.

WATCH: How a Tick Digs Its Hooks Into You
Watch this video from National Public Radio on how ticks latch on.

Blacklegged Tick Habitat

Where do we find blacklegged ticks? 

  • Blacklegged ticks live in wooded, brushy areas that provide food and cover for white-footed mice, deer and other mammals.
    • This habitat also provides the humidity ticks need to survive.
  • Exposure to ticks may be greatest in the woods (especially along trails) and the fringe area between the woods and border. Rarely, blacklegged ticks may be found in more open areas (such as yards) that are near wooded habitat so it is important to be on the lookout for ticks when in or near wooded areas.
  • Blacklegged ticks search for a host from the tips of low-lying vegetation and shrubs, not from trees. 
    • Generally, ticks attach to a person or animal near ground level.
  • Blacklegged ticks crawl; they do not jump or fly. They grab onto people or animals that brush against vegetation, and then they crawl upwards to find a place to bite.
  • White-tailed deer live throughout Minnesota, but blacklegged ticks are not found everywhere that deer live. 

Tick Photos

Adult female blacklegged tick on a thumb.Adult female blacklegged tick on a thumb.

	Blacklegged tick nymph on a fingernail.

Blacklegged tick nymph on a fingernail.

Adult female (left) and male (right) blacklegged ticks on leaf.

Adult female (left) and male (right) blacklegged ticks on leaf.

	Adult blacklegged tick (left) and adult American dog tick (right) on pant leg.

Adult blacklegged tick (left) and adult American dog tick (right) on pant leg.

	Two adult female blacklegged ticks (left) and one male blacklegged tick (right) on pant leg with finger for size comparison.

Two adult female blacklegged ticks (left) and one male blacklegged tick (right) on pant leg with finger for size comparison.

Updated Wednesday, 04-Apr-2018 13:10:35 CDT