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The Invasive Longhorned Tick and Its Potential Health Effects

Linda Crampton is a writer and teacher with an honors degree in biology. She loves to study nature and write about living things.

An Animal of Concern

The longhorned tick feeds on the blood of both birds and mammals, including humans. In some parts of the world, it carries bacteria and viruses that can infect people and cause disease. In these areas it’s classified as a public health threat. The tick is native to East Asia but is also found in other areas, including Australia and New Zealand. It has recently been discovered in the continental United States and is spreading. It hasn't yet been shown to transmit human diseases in the U.S. but is being monitored carefully.

The scientific name of the longhorned tick is Haemaphysalis longicornis. It’s also known as the bush or cattle tick. To the unaided eye, the animal is very small and can be mistaken for a speck of dirt when it hasn’t eaten human or animal blood recently. It’s red-brown in colour and has darker markings. When the animal is engorged with blood, its appearance changes dramatically. The swollen tick is predominantly grey and its markings often appear to be yellow or pale red, as shown in the photo above. A magnified view of the unfed tick can be seen in the opening screen of the video below.

Ticks aren't insects. They belong to the phylum Arthropoda and the class Arachnida. Spiders also belong to this class. Hard ticks belong to the family Ixodidae (pronounced iks-sod-i-dee) within the class Arachnida.

External Anatomy of Ticks

Ticks are small animals with an oval body. They have four pairs of jointed legs, like spiders. The ends of the legs are hooked. Hard ticks (including the longhorned tick) have a plate-like structure on their back called a scutum. The female's scutum is shorter than the male's.

The capitulum or gnathosoma (feeding structure) of the animals can be seen in the "head" region of the body. Many North American ticks have a long and narrow capitulum, but the longhorned tick has a short and wide one. On each side of the capitulum is a sensory structure called a pedipalp. In between the two pedipalps are the chelicerae, which cut through the skin of the host, and the hypostome, a long, narrow, and often barbed structure that acts like a harpoon.

The hypostome is used to anchor the tick to its food source. This is an important function because ticks need to stay anchored to their host for a long time in order to take up enough blood through their mouthparts. Some ticks secrete a substance that acts as a cement to hold the hypostome in place. The structure is sometimes grooved to facilitate the flow of liquid.

Other Features of the Animals

Some ticks have eyes, which are located on the sides of the scutum. The eyes can detect light and movement. At least some species have a structure called the Haller's organ in the outermost segment of each foreleg. This organ seems to detect a wide variety of stimuli, including specific chemicals, humidity, and heat.

On each side of the body behind the last leg is an opening called the spiracle, which leads to the respiratory system. (The mouth isn't used in respiration.) The anus is located towards the rear of the animal on its undersurface. In the middle of the undersurface is the opening of the reproductive system.

A close-up view of an engorged Ixodes ricinus

A close-up view of an engorged Ixodes ricinus

The common name of Ixodes ricinus is the castor bean tick. The photo above gives a close-up view of typical hard tick features. The capitulum, legs, and a spiracle can be seen. The dark plate behind the capitulum is the female's scutum. The smaller scutum of the female compared to that of the male allows her body to expand when she swallows blood. Adult male ticks don't appear to feed on blood, but they may absorb some body fluids from a host.

The Longhorned Tick

If it hasn't eaten recently, the adult longhorned tick is only 3 to 4 mm long. Like other ticks, when it's swollen with blood its appearance changes so much that it looks like a different animal. It's often said to resemble a raisin in appearance if not in colour. It may look like a swollen sac, or it may be swollen and also have indentations as raisins do. Apart from its appendages, it's grey or grey-green in colour. During this stage, the tick is about the size of a pea.

Like other ticks, the longhorned species finds a host by a behaviour called questing. The tick climbs to the top of a tall plant and positions itself with its head facing downwards. It then holds its front legs outwards ready to latch onto a passing animal. The tick may wave its legs around as it quests. Ticks don't jump, so they have to quest very near the area where animals or humans travel. They can detect the presence of a host in a variety of ways. Certain chemicals, such as exhaled carbon dioxide, body heat, and vibrations are clues that tell a tick that a host is nearby.

Life Cycle of Haemaphysalis longicornis

The life cycle of the longhorned tick contains four stages: egg, larva, nymph, and adult. The tick exists in male and female forms and reproduces sexually. After fertilization, the female generally lays 800 to 2000 eggs in the soil in mid-summer. Females die after laying eggs. Males often die after fertilization.

Each egg hatches into a larva, which is very small and has only six legs. Like the adult, it feeds on blood. After several days, it molts and turns into a larger nymph. The nymph has eight legs and is about 2 mm long. It's the overwintering stage in the life cycle. The longhorned tick is known for its ability to survive cold winters. In the spring, the larva eats blood and then molts to become an adult.

The longhorned tick also has the ability to reproduce by parthenogenesis, which is the process in which an unfertilized egg produces an embryo. The existence of parthenogenesis means that the female has the ability to clone herself and doesn't need to take the time to find a male in order to reproduce.

According to an article written by University of Virginia scientists (referenced below), while Asian populations of the tick exist as males and females, the American population is thought to be entirely female and to reproduce by pathenogenesis.

The tick lives in tall grass when it isn't feeding on blood from a host. It settles near the surface of the soil where moisture prevents it from drying out. It feeds on the blood of farm animals, wildlife, pets, and humans. At the moment, it seems to be infesting animals instead of humans.

Longhorned Ticks in the United States

The longhorned tick has occasionally been found on animals arriving in the United States at ports, but until quite recently it wasn't believed to have become established in the country. It was discovered in the U.S. on August 1st, 2017 but wasn't identified until November 9th. The discovery was made in New Jersey and involved a woman and her pet sheep.

The woman discovered a heavy infestation of ticks on her pet and took some of them to the authorities to be identified. The authorities found that the woman had numerous ticks on her clothing. They later discovered that her property contained many individuals of the longhorned species. Larvae, nymphs, and adults were discovered on the sheep.

The sheep was the only domesticated animal on the property and hadn't left the area for years, so the arrival of the ticks was puzzling. The infested area was later cleared of ticks, but the investigators say that some other infested animals in the region may have been missed.

Since the original discovery in New Jersey, the tick has been found in other parts of the state as well as in other states in the country. It appears to be spreading.

As of October 10, 2020, longhorned ticks have been found in Arkansas, Connecticut, Delaware, Kentucky, Maryland, New Jersey, New York, North Carolina, Ohio, Pennsylvania, Rhode Island, South Carolina, Tennessee, Virginia, and West Virginia.

— Centers for Disease Control and Prevention

Anaplasma phagocytophilum in cultured white blood cells

Anaplasma phagocytophilum in cultured white blood cells

Potential Health Problems

It's unknown whether longhorned ticks are harmful to humans in the United States. There is currently no evidence that they are. The fact that they transmit disease in some parts of the world is a concern, however. Investigators think that the ticks are currently a greater threat to animals than humans, but this situation could change. The situation is being monitored closely with respect to its potential effects on agriculture and on human beings.

In some parts of the world, the longhorned tick transmits the following pathogens to humans:

  • Anaplasma phagocytophilum, a bacterium that causes a disease called human granulocytic anaplasmosis and is present in other ticks in the United States
  • Rickettsia, another bacterial genus that is already transmitted by some U.S. ticks
  • Species of Borrelia bacteria (One species of this bacterium causes Lyme disease in the U.S.)

In some areas, the longhorned tick also spreads the Powassan virus, which causes encephalitis, or inflammation of the brain. Like the bacteria mentioned above, the virus is already present in some ticks in the United States.

In addition, the tick is known to transmit the SFTS virus, which isn't present in other U.S. ticks. The name of the virus is an abbreviation that stands for severe fever with thrombocytopenia syndrome. Thrombocytopenia is a disorder in which the number of thrombocytes (or platelets) in the blood is abnormally low. Platelets play a vital role in the blood clotting process. The disease reportedly has a ten to thirty percent mortality rate.

A tick-borne disease is passed from one organism to another by the arachnid. Pathogens enter the tick when it withdraws blood from one host and then contaminates another host's bloodstream as it feeds on the animal.

A Human Bite by the Tick in the US

In June 2019, the first known bite from the tick was announced. The man who received the bite lives in Yonkers, New York. He hadn't been outside his home county for thirty days prior to the bite. His doctor prescribed medication to prevent Lyme disease, since it was assumed that the tick was Ixodes scapularis.

The man saved the tick and decided to take it to the Lyme Disease Diagnostic Center. The animal was eventually identified as a longhorned trick. Officials found the ticks on the man's lawn, on a park across the road from his home, and on a nearby public trail. This was the first time that the arachnid had been found in New York.

The man didn't get sick during the three months of monitoring after the bite. Nevertheless, the situation is worrying because it indicates that the longhorned tick is spreading and that its population is doing well in the United States.

Avoiding and Removing Ticks

According to experts, there is no need to panic about the longhorned tick with respect to its effects on humans. It is recommended that people take precautions in tick infested areas, however, especially since these will help to prevent the transmission of diseases by other ticks.

  • Avoid travelling through areas with tall grass or dense plant growth. If you do travel through these areas, follow a trail and stick to the centre of the trail so that you don't brush against plants. The same rules apply to pets travelling through the area.
  • Tuck the legs of pants into socks so that skin isn't exposed. Also tuck in shirts and wear long sleeves.
  • Wear light-coloured clothing so that ticks are easier to see.
  • Perform a tick check of human bodies and pets after travelling in a potentially infested area. (Ticks don't transmit disease immediately after attaching to a human. The time varies.)
  • Remember to check hidden areas of the body where ticks like to hide, such as under the armpits, in the groin, and on the scalp.
  • Consider treating skin, clothing, pets, and farm animals with a tick repellent. (This step requires careful research into the safety of the repellent.)
  • If a tick is discovered, remove it with tweezers. Grab hold of the animal close to the skin. Try to pull it out slowly and in a straight line. Twisting the animal may cause body parts to break off and stay in the wound. Wash the wound once the tick has been removed.

Ticks are known to transmit a variety of unpleasant diseases in North America. It's therefore important to take steps to avoid them, whether or not the longhorned tick is dangerous. Hopefully this invader won't hurt us, but in case it does, we need to be proactive.


  • Hard and soft ticks and disease from the University of Missouri Extension
  • Exotic tick fact sheet from the State of New Jersey Department of Agriculture
  • Facts about longhorned ticks from Virginia State University Extension
  • Self-cloning tick in New Jersey from and Assistant Professor at Rutgers University via The Conversation
  • Haemaphysalis longicornis found on a New Jersey sheep from NPR (National Public Radio)
  • Detection of the animal in Arkansas from the NPS (National Park Service)
  • First known human bite from a longhorned tick from CIDRAP (Center for Infectious Disease Research and Policy), University of Minnesota
  • Asian longhorned tick information from the CDC (Centers for Disease Control and Prevention)

This content is accurate and true to the best of the author’s knowledge and does not substitute for diagnosis, prognosis, treatment, prescription, and/or dietary advice from a licensed health professional. Drugs, supplements, and natural remedies may have dangerous side effects. If pregnant or nursing, consult with a qualified provider on an individual basis. Seek immediate help if you are experiencing a medical emergency.

Questions & Answers

Question: What are the longhorned tick’s enemies?

Answer: I can tell you about some enemies of ticks in general, but not specifically of the longhorned tick. Some birds, spiders, and ants feed on ticks, though the animals aren’t their main food. Certain pathogenic (disease-causing) fungi have been helpful in controlling the animals because they enter a tick and kill it. Researchers are exploring the use of parasites such as nematodes (roundworms) in the control of ticks. The parasites may be useful in some areas.

© 2018 Linda Crampton


Linda Crampton (author) from British Columbia, Canada on November 26, 2018:

Thank you very much for the comment and for sharing the link, Glenn. Ticks can certainly produce nasty effects. I hope they don't cause you any problems where you live.

Glenn Stok from Long Island, NY on November 26, 2018:

I’m an avid hiker and here on Long Island there are a lot of ticks. Lyme decease is quite common here. I'm always cautious to check that I don’t have any ticks on me after a hike, and knowing what you explained in this article makes me want to be even more cautious. I found your article very informative and helpful, Linda, and I’m passing the link to it on to other hikers.

Linda Crampton (author) from British Columbia, Canada on August 29, 2018:

Having Lyme disease twice sounds horrible. I hope you don't experience it again, Claudia. Thanks for reading the article despite the unpleasant effects of ticks in your life.

Claudia Mitchell on August 29, 2018:

I had to get brave enough to come check this article out Linda. I'm just getting over Lyme disease for a second time. Ticks are quite prevalent in our neck of the woods so I'm wary of them. And now there is another one. Yuck!

Linda Crampton (author) from British Columbia, Canada on August 07, 2018:

I hope your pets don't develop any problems, Lisa. Ticks can be very unpleasant.

Lisa Murphy on August 07, 2018:

I just found one on my dog last week, and my cat had one last year! They are awful. I have been watching to see if they have any symptoms from this.

Linda Crampton (author) from British Columbia, Canada on July 28, 2018:

Hi, Devika.The thought of ticks often seems to make people feel itchy! Thanks for the visit.

DDE on July 28, 2018:

One look at the photo makes me feel itchy. Informative and another lesson from you.

Linda Crampton (author) from British Columbia, Canada on July 26, 2018:

Hi, Adrienne. Thanks for sharing your experience. Ever since I wrote the article I've been very aware of the tall grass on a pathway by my home. The grass has been cut, thankfully, but I'm sure it will be tall again soon!

Adrienne Farricelli on July 26, 2018:

Eeeek, I hate ticks (I am sure nobody loves them). I still have nightmares of ticks back from when I lived in the small town of Rothville, Missouri. Little Laura Ingalls was raised near this town for a short part of her childhood, and then moved. I always joked that the Ingalls family moved out due to too many bugs and when I watch the TV show and see her running through the tall grass I imagine all those ticks climbing. I wished there was a way to get rid of them from this planet. Thanks for the informative article.

Linda Crampton (author) from British Columbia, Canada on July 15, 2018:

Hi, Pamela. I know what you mean by saying that ticks are creepy. They are definitely animals to avoid.

Pamela Oglesby from Sunny Florida on July 15, 2018:

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Ticks are just creepy. I had to remove a tick on one of by boys and uced tweesers as that seeme the only way. Thanks for all the tips to avoid them.

Linda Crampton (author) from British Columbia, Canada on July 14, 2018:

Hi, Genna. Yes, protecting our pets is very important. It's good to think about the possibility of tick bites, especially when we go to an area that we haven't visited before. Thanks for the comment.

Genna East from Massachusetts, USA on July 14, 2018:

Ticks have always given me the willies. In our part of the country, it is the tick(s) associated with Lyme Disease and/or Rocky Mountain spotted fever. I was surprised to learn that the Longhorn is now in our neck of the woods, so to speak. Protecting our pets is so important. Excellent article.

Linda Crampton (author) from British Columbia, Canada on July 12, 2018:

Hi, Bede. I hope you don't experience many tick bites this summer! I've seen quite a similar

Greek origin for the term parthenogenesis as you.

Bede from Minnesota on July 12, 2018:

Linda, the ticks have been endemic where I live, specifically wood ticks. It’s interesting to know some of their features and abilities. More than once, though, I’ve had a blood-engorged tick on me. If my Greek is correct, parthenogenesis means “pure beginning.”

Linda Crampton (author) from British Columbia, Canada on July 12, 2018:

Thanks for the visit and the comment, Manatita. Ticks can be scary, though they are interesting creatures. Nature and its origin are certainly awesome to consider.

manatita44 from london on July 12, 2018:

A little scary, that one, Alicia. So tiny and with such a dangerous potential, even for us humans.

Another thought that I held, is that they are so similar to us! They breathe, eat, sleep, reproduce, go to the bathroom and need the right environment in order to survive. Isn't God awesome!

Linda Crampton (author) from British Columbia, Canada on July 11, 2018:

Hi, Suhail. I'm sorry for the people in the USA, but I'm glad we don't have longhorned ticks here. I hope they never arrive!

Suhail Zubaid aka Clark Kent from Mississauga, ON on July 11, 2018:

Informative hub!

Thanks God I live in Canada and do not venture out to southern USA, but we do have tick problem. I use the cure prescribed by the vet.

Linda Crampton (author) from British Columbia, Canada on July 10, 2018:

Hi, Peggy. It's good that the engorged ticks are easier to see, though it would be nice to catch them before they've drunk blood. I'm sorry for people who develop Lyme disease, such as your parents' friend. The disorder can be a big problem.

Peggy Woods from Houston, Texas on July 10, 2018:

When we lived in McAllen, Texas many years ago we had to constantly check our dogs for ticks and fleas. There seemed to be an abundance of them down there at the time. It was easy to spot the engorged ticks on the pets.

A good friend of my parents came down with Lyme Disease. It was not caught early and affected him horribly for a long time.

Linda Crampton (author) from British Columbia, Canada on July 10, 2018:

Hi, Heidi. I agree. Protecting pets as well as people is important. Thanks for the visit.

Linda Crampton (author) from British Columbia, Canada on July 10, 2018:

Hi, Mary. Yes, we need to do what we can to avoid ticks. This is definitely a case where it's important to be safe and not sorry.

Heidi Thorne from Chicago Area on July 10, 2018:

Oh boy! If you have dogs, a good reason to use preventives for ticks. Super informative. Thanks!

Mary Norton from Ontario, Canada on July 10, 2018:

We have heard that some were found in our area so our friends are careful in checking their pets and protective clothing. it is so hot here now that one can no longer wear long pants but maybe just avoid tall grasses but we have lots of trees around.

Linda Crampton (author) from British Columbia, Canada on July 10, 2018:

Thank you very much for the comment.

YSSavvy from Saudia Arabia on July 09, 2018:

A very informative, yet amazing article!

Linda Crampton (author) from British Columbia, Canada on July 09, 2018:

I appreciate your comments, Jackie. They are all interesting!

Jackie Lynnley from the beautiful south on July 09, 2018:

I forget you are not from here sometimes Linda! Glad to hear you have little chance for it and I am just not sure what tick this is but it is the Rocky Mountain one for sure and it can cause Lyme's the doctors said but maybe catching it in time prevented that, not sure, but they did test me for that. I am seriously getting out of here as soon as I can though, believe me! I am also not getting any pets while I am still here. It is a very miserable disease and can cause long term problems as you say.

OK, I am not going to monopolize your article, now. Just could well relate to this one!

Linda Crampton (author) from British Columbia, Canada on July 09, 2018:

A tick-borne disease that we have to watch out for in my area is Lyme disease. Rocky Mountain spotted fever is rare in British Columbia, I'm glad to say. I've heard of people having some unpleasant experiences with Lyme disease, though.

Jackie Lynnley from the beautiful south on July 09, 2018:

Yes, everyone said you pick them up in high grasses and I got rid of my hens because I assumed that is where I picked them up but the one I had on me a couple of days ago had to have fallen from a tree overhead! I have not been near any grasses.

I keep constant check and it is beginning to be very aggravating. It is a very painful thing to have. Do be careful.

I think you can check to see if the ones that cause disease has been spotted in your area and there had not been any in my area before my bites so they are apparently spreading!

Oh, and mine hid in the tight crevice of my ear, or the only one I found. The other must have eventually been washed away but not before doing it's damage.

Linda Crampton (author) from British Columbia, Canada on July 09, 2018:

Oh my goodness! It sounds like I and my dogs have been very lucky with respect to tick exposure based on the comments that I'm reading. How horrible to have had Rocky Mountain spotted fever twice! I hope you don't get bitten by a tick again this summer, Jackie.

Jackie Lynnley from the beautiful south on July 09, 2018:

Horror of horrors, Linda! I have been bitten by two different ticks (well, probably the same kind) and have had Rocky Mountain Spotted Fever twice! I did not get Lyme's Disease thank goodness but the antibiotic hurt me about as bad as the RMSF and I live in constant fear of being bitten again and just a couple of days ago while outside (I live in the southern US) I looked down and saw one fast crawling up my sleeve!!

Linda Crampton (author) from British Columbia, Canada on July 09, 2018:

Hi, Flourish. The sheep incident was strange. I hope more is discovered about it. Thank you for the visit.

FlourishAnyway from USA on July 09, 2018:

Ticks carry some nasty pathogens although this one doesn’t seem to affect humans at this time. The case of the pet sheep with the infestation was really strange given that it was newly reported and discovered. It seemed to pop up out of nowhere.

Linda Crampton (author) from British Columbia, Canada on July 09, 2018:

Hi, Alexander. They can certainly be dangerous, depending on whether they contain microbes that make us sick and on what illnesses these microbes cause. It's always wise to be cautious about tick bites!

Alexander James Guckenberger from Maryland, United States of America on July 09, 2018:

Ticks are very dangerous.

Linda Crampton (author) from British Columbia, Canada on July 09, 2018:

Hi, Bill. An infestation sounds horrible. I'm glad you found the ticks on your dog, too, and that you were able to remove them.

Linda Crampton (author) from British Columbia, Canada on July 09, 2018:

Thanks for the comment, Chris. I'm glad you were able to find the ticks on your dog.

Bill Holland from Olympia, WA on July 09, 2018:

We are currently experiencing an infestation of ticks in our area. There are certain areas around here we cannot walk the dogs. We spent a great deal of time last month removing ticks from our puppy, but we seems to have things under control now.

Chris Mills from Traverse City, MI on July 09, 2018:

I have to watch for ticks here in Montana since I'm out in the forests so much. I've found two on my dog, none on me. Good and informative article, Linda.

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