Ticks have existed for 90 million years, with more than 800 known species throughout the world. Of these, 200 can be found in the United States. Often thought to be insects, these pests are actually part of the spider family.
Ticks are parasites that feed on the blood of humans and animals. They are common foes of house pets and people who spend time outdoors.
What do ticks look like?
Ticks range in size from nearly-visible to 1/4” and their bodies are flat before feeding. They are reddish-brown, orange-brown, brown, or black in color. Some ticks will turn a greyish-white when their bodies become engorged, or rounded, after a meal.
The body of a tick consists of a head, thorax, abdomen, and four pairs of legs. They also have three important mouthparts — chelicerae, hypostome, and palps — used to pierce the skin and draw blood from the host. Ticks are divided into two groups: hard and soft. Hard ticks have a hard plate, called a scutum, on their backs. Soft ticks do not have a scutum but do possess leather-like skin.
The hard ticks’ development cycle takes them from egg to larvae to nymph to adult in what is often called a three-host cycle. Ticks die shortly after mating and laying eggs on the ground. The eggs hatch into larvae. At the larval stage, ticks attach to the first host, and once they have had a sufficient blood meal, they detach and return to the ground where they develop into nymphs. The nymph — which is sometimes called a seed tick — attaches to a second host, once again feeding. When sated, the nymph leaves the host, returning to the ground to finish its evolution into an adult tick. Both male and female attach to a third host and mate, beginning the cycle once again.
The lifecycle of soft ticks varies, as they remain in the nest of their host and may feed on the same animal or group of animals during their development.
What are the unique characteristics of ticks?
Ticks eat the blood of mammals, birds, amphibians, and reptiles, with specific types preferring certain hosts. While they require a blood meal to develop, some ticks can survive as long as two years without feeding.
Soft ticks typically feed on their host for an hour or less, during which time they are capable of transmitting disease. Hard ticks generally feed for many hours, or even days, and pass diseases to their host during the end of the feeding period.
What are the habits of ticks?
Ticks do not have the ability to fly or jump. Instead, they crawl onto tall grasses, bushes, or trees and use their legs to latch onto hosts — which is called questing — as they pass by. Once a host is found, the tick searches the body for a warm, moist location with easy access to blood. Common areas ticks target on a human include the scalp, neck, groin, armpits, behind the ears and knees, and around the waist. On dogs, soft ticks are often found in the ears. While they require a blood meal to survive and develop, ticks drop from their hosts after being adequately fed. Hard ticks actually spend the majority of their time on the ground rather than on a host.
Ticks are active year-round, though many tend to become dormant when the temperature drops below 45°F or is very hot and dry. Because ticks cannot drink water, most require areas with high humidity (85% or greater) to remain hydrated.
Where are ticks commonly found?
Ticks are located throughout the United States. They migrate to areas with temperate climates and easy access to hosts. Of the seven types of ticks known to attack humans, five have a strong presence in the southeastern states. They seek out grassy or wooded areas and, in the early stages of development, make their homes in decomposing leaves.
What are the risks of ticks?
Behind mosquitoes, ticks are the second largest transmitter of disease to humans, introducing bacteria, viruses, and protozoa to their hosts. In the United States, seven types of ticks are believed to be especially harmful to people and animals:
- The American dog tick, found east of the Rocky Mountains and in the Pacific coastal area, transmits tularemia and Rocky Mountain spotted fever.
- The black-legged (or deer) tick, which resides in the Northeast and upper Midwest, carries Lyme disease, Powassan disease, babesiosis, anaplasmosis, ehrlichiosis, and Borrelia miyamotoi.
- The brown dog tick, found in all continental states, transmits Rocky Mountain spotted fever.
- The Gulf Coast tick is present along the Gulf of Mexico and Atlantic coasts. It carries a form of spotted fever know as Rickettsia parkeri rickettsiosis.
- The lone star tick is common in the Southeast and East. It transmits tularemia, Heartland virus, STARI (or southern tick-associated rash illness), and two bacteria that cause ehrlichiosis.
- The Rocky Mountain tick is at home in the Rocky Mountain states between 4,000 and 10,500 feet. It is responsible for spreading Rocky Mountain spotted fever, tularemia, and Colorado tick fever.
- The Western black-legged tick, found in Northern California and other Pacific coast areas, transmits Lyme disease and anaplasmosis.
Ticks are capable of transmitting more than one disease at a time during a single feeding. Symptoms of diseases spread by ticks may include pain, rash, swelling, chills, muscle aches, headache, fever, nausea, fever, fatigue, inflammation of the brain, and more. In some cases, tick-induced diseases are fatal.