There are two types of black tick: eastern — Ixodes scapularis— and western — Ixodes pacificus. Both are more commonly known as deer ticks, are very similar, and are members of the arachnid family. The black tick is a parasitic organism which feeds on a variety of hosts over its two-year life cycle. This tiny creature, like many other tick species, is a common carrier, or vector, of a variety of bacterial infections, including Lyme disease and babesiosis.
The black tick is very common particularly across North America, and can be easily picked up by humans if precautions are not taken. A member of the arachnid, or spider, family, the black tick is a parasite unlike the spiders to which it is related. A parasite is an organism which uses another organism for food and shelter and to complete its reproductive cycle.
As a parasitic organism, the black tick feasts upon the blood of its chosen host, switching to a new host after each stage of the life cycle. After hatching from the large clutch of eggs, the first stage, or larval, tick finds a small mammal. One of the most common hosts for larval black ticks is the white-footed mouse, but any small mammal will suffice. Once on the host, the tick burrows its comparatively large mouth parts beneath the surface of the skin and begins to feed on the blood of the mammal.
It is at this point that the larval tick is most likely to contract the bacteria which causes Lyme disease and other potentially harmful or lethal bacteria. Ticks can also contract and carry other smaller parasites, such as the single-celled, or protozoan, Babesia microti which can pass to large mammals such as cattle, horses, and humans via a bite from an infected tick. If a larval tick bites an infected host, the tick will carry the smaller parasite or bacteria through to maturity, potentially passing the infections to each host it feeds upon.
Once large enough, the larval tick detaches itself and sheds its exoskeleton as it transforms into a nymph after several months. The cycle then repeats until the nymph has gained enough nutrients from the blood of its host to develop into a full-grown adult. The adult black tick attaches to a new host, which tends to be a much larger mammal, such as a deer, a cow, or a human.
The mature black tick once more burrows the mouth parts through the skin of the host, where it injects a chemical that thins the blood and prevents clotting. Feeding for a mature female black tick can last for several weeks and involve multiple hosts. Eventually, the tick drops from the final host and lays up to 300 eggs on the ground before dying, completing its two-year life cycle.