Learn about the Deer Tick or Blacklegged Tick

There are about 90 species of ticks in the United States, but the deer tick often gets the worst rap. That's because the deer tick, sometimes called the deertick, is a vector for Lyme disease and other illnesses. Now, you may be wondering, just "what is a deer tick?" The simple answer is that it is an ectoparasite that requires blood meals to grow. But if you want to know more, keep reading.


These ticks, which are also known as black legged or the more correct "blacklegged" ticks, are among the smallest of the species. Adults are just one-eighth of an inch long, and nymphs can be as small as the head of a pin. Both adults and nymphs have eight legs. Larvae, which only have six legs, are nearly invisible to the naked eye – they are about the size of the period at the end of this sentence.

They have black legs, as their name suggests, and can be distinguished from other tick species by their orange to red bodies.

Deer ticks, Ixodes scapularis, are in the family Ioxidae, which means that they are hard-shell ticks. Soft-shell or soft ticks are in the family Argasidae, and have a different life cycle.

Circle of life

Hard-shell ticks fall into one-host, two-host or three-host categories – meaning they require that many hosts during their development. The blacklegged tick is a three-host tick.

For the deer tick, life begins and ends on the ground. The entire life cycle of blacklegged ticks takes two to three years to complete.

Larvae hatch in the leaf litter of wooded or brushy areas and wait for a host to pass by. Common hosts are white-footed mice, other small mammals and birds. Their first blood meal can take up to three days to complete, after which they drop back to the ground and undergo their first molt. July through September is peak season for active larvae. After molting is complete they develop into the nymph stage.

Nymphs, active from May through August, are known to attach themselves to mice, chipmunks, voles and other small mammals. However, they will also feed on dogs, cats or humans if the opportunity presents itself. The blood meal for this life stage can take up to four days. When they drop to the ground, they will once again hide in the leaf litter, or take refuge in animal burrows. They will undergo another molt, and emerge as adult deer ticks in the autumn.

Adults will begin to emerge in October, and can remain active as long as the temperature stays above freezing. Their season winds down in May. Blacklegged ticks somewhat ironically prefer white-tailed deer as their hosts. The adult ticks will crawl up brush or tall grass and "quest" for a host. Because ticks cannot jump or fly, they wait with outstretched legs for a host animal to brush past them. It is the adult females of this species that require another blood meal; males do not eat again. They wait for the deer, other large mammals or people and pets to pass by before attaching for that meal. Females drop back into the leaf litter to overwinter. In May, the females will lay one batch of eggs before dying. A single female can lay between 1,500 and 2,000 eggs in this batch.


It is important to note that most tick larvae hatch disease-free. They encounter the bacteria they spread during their nymph and adult stages. Blacklegged ticks are often infected with – and transmit – anaplasmosis, babesiosis and Lyme disease.

According to the Centers for Disease Control (CDC), people most often contract Lyme disease through the bite of an infected nymph, though adults can also transmit it. Borrelia burgdorferi, the bacteria that causes Lyme disease, is not transmitted immediately. In most cases, the CDC says an infected tick must be attached and feeding for 36 to 48 hours in order to pass along the disease.

The mid-Atlantic, Northeast and North Central United States are home to the blacklegged tick, which spreads the disease in those regions. On the West Coast, and in parts of Arizona, Utah and Nevada, the disease is spread by a relative – the western blacklegged tick, Ixodes pacificus.