How Ticks Get On You

And What You Can Do to Avoid Being an Unwilling Host

Wood Tick
ArtBoyMB / Getty Images

Although you may occasionally suffer the misfortune of finding a tick on your body, you can rest assured the little sucker didn’t jump on you. That's because ticks don’t jump. So, just how do these pesky arachnids grab onto humans and pets? Ticks are one of nature's craftiest stowaways. As you probably know, ticks are blood-feeding parasites. What you might not know, however, is that they are specially equipped to sense their prey coming—meaning a warm-blooded host—and surreptitiously tag along for the ride.

Haller's Organs and a Tick's Keen Sense of Smell

Almost all ticks use a behavior called "questing" to ambush potential hosts. When in search of a blood meal, ticks crawl up plant stems or tall grass and simply extend their front legs in the questing posture (like the black-legged tick pictured above).

Ticks have special sensory structures on their front legs called the Haller’s organs that they use to detect an approaching host. In 1881, scientist G. Haller published the first description of these structures, although he misunderstood their purpose. Haller believed the structures were auditory sensors, when in fact they proved to be olfactory sensors. That means, when a tick sits on a blade of grass with its front legs extended, it is effectively sniffing the air for your scent.

What’s remarkable, however, is just how well the tick can smell prey and sense even the slightest movement. Using its Haller’s organs, a tick can detect the carbon dioxide you exhale with each breath and the ammonia in your sweat. Even the most well-groomed hiker can’t avoid detection by the Haller’s organs because they can also sense changes in temperature as you approach.

How Ticks Actually Get on You

When a tick knows you are nearby, it grabs hold of your leg as you brush past the vegetation on which it's waiting. Most ticks behave passively in this regard, relying on you to come to them. Some ticks, however, particularly those in the genus Hyalomma, will actually make a mad dash in your direction as soon as they smell you coming.

Scientists use this behavior to their advantage when sampling an area for ticks. When a researcher drags a square of white felt across the ground, any ticks in its path will sense the movement and grab onto the felt. Once they've attached themselves, they're visible against the white backdrop and can be counted or collected for further study.

Fast Facts: How to Keep Ticks From Getting On You

Understanding tick behavior can help you minimize your risk of tick bites. Here are some tips to help you avoid becoming a host.

  • Avoid walking through areas of thick or high vegetation.
  • Keep your legs covered. Wear pants, shoes, and socks if at all possible.
  • Use an effective tick repellent and reapply as directed.
  • Wearing a hat won't really help. When you do find a tick on your upper body or in your hair, it's nearly always because the critter managed to crawl there from your leg. 

Checking for Tick Bites & Treatment

Whether you've been out tending your garden, walking your dog through the neighborhood, or traipsing through the woods, make sure to conduct a thorough, full-body tick check immediately after returning indoors. If you're lucky, you can remove most ticks before they’ve enjoyed a meal of your blood (and possibly infected you with a disease-causing pathogen). As they do tend to travel, make sure to check your back, scalp, and behind your ears, as well as the skin beneath waistbands and leg bands of undergarments.

If you do find a tick lodged somewhere on your body, take care when removing it. Use a tweezer and pull on the tick out without crushing it. If possible, put the culprit in a container and freeze it, and then thoroughly wash your hands and the site of the bite. If you get a rash, fever, infection, or flu-like symptoms, see your doctor, and bring the tick with you. If you think you may have contracted Lyme disease, insist on getting tested for it. The earlier the diagnosis, the more effective the treatment.

Sources

  • Vredevoe, Larisa. "Tick Biology." UC Davis Department of Entomology and Nematology.
  • Coons, Lewis B., and Marjorie Rothschild. "Ticks (Acari: Ixodida)." In Encyclopedia of Entomology, edited by John L. Capinera. The University of Memphis.
  • Henry, George, and Faulkiner, Nuttall. "On the Structure of 'Haller’s Organ' in the Ixodiodea.Parasitology, Vol. I. No. 3, (October 1908). Google books.