Q: What are Asian longhorned ticks?
A: The Asian longhorned tick (Haemaphysalis longicornis; ALHT) has been introduced to the United States and can be found in Ohio. ALHT females can reproduce without mating and lay up to 2,000 eggs, which allows them to quickly establish large populations. They have been reported on more than two dozen species including sheep, goats, horses, cattle, chickens, dogs, cats, and humans. Among wildlife species, ALHT are most commonly reported on deer and raccoons.
Q: Can they make humans or animals sick?
A: Livestock may become heavily infested with large numbers of ALHT causing distress that can lead to decreased production and growth, aborted or still births, and death. These ticks may also transmit bovine theileriosis causing anemia in cattle, which can be fatal. Few other animal or human pathogens have been reported in ALHT populations in the U.S. and they have not yet been linked with cases of human disease. However, these ticks have demonstrated the capability to acquire and transmit several human and animal pathogens in other countries and in the laboratory.
Q: What should I look for?
A: Regularly check your animals for ticks by scratching and feeling around the ears, shoulders, groin, armpits, and anus of your animals. ALHT appear small, brown, and plain (lacking color pattern) when unfed but may appear grayish when engorged with blood. Unfed adults are roughly the size of sesame seeds but can swell to the size of a pea when engorged. Juvenile stages (larvae and nymphs) are so small they may go unnoticed or resemble tiny, fast-moving spiders. All three life stages can occur at the same time, but nymphs are most active in the spring followed by adults in the summer and larvae in the fall. ALHT can also be active in winter. Although many ticks can look alike to the naked eye, the following suspicious tick encounters are characteristic of ALHT:
- observing unusually high numbers (hundreds to thousands) of ticks or little “spiders” on animals or equipment
- being swarmed by ticks upon entering a field
- observing clusters of ticks on the tips of vegetation (may look like clumps of seeds)
Q: How can I prevent ticks?
A: Keep grass and weeds short. Clear brush from feedlots and pastures. Talk with a veterinarian about tick prevention for your animals. Prevent tick bites on yourself by wearing tick repellent, long sleeves, and pants, and by tucking pants into socks to limit access to your skin. Perform a thorough tick check whenever you return from the outdoors. Remove all ticks immediately by grasping the tick close to the skin with tweezers and pulling gently upwards. If bitten, save ticks for identification, mark your calendar, monitor yourself for any signs of illness, and contact your healthcare provider. For more information on tick safety, visit the Ohio Department of Health website.
Q: What should I do if I see ticks?
A: If you see ticks that resemble ALHT or experience any suspicious tick encounters, please submit ticks to The Ohio State University for identification. Send an email to email@example.com for instructions. Immediately report large numbers of ticks on livestock to ODA’s Division of Animal Health by calling 614-728-6220.
An integrated pest management strategy is needed to manage ALHT that includes biosecurity, scouting, animal treatment, and pasture management.
Biosecurity: Check new stock thoroughly for ticks prior to introduction to your farm.
Scouting: Check for ticks when working animals or prior to moving them to a new pasture.
Acaricides (Animal Treatment): Treat animals for ticks based on scouting, examination findings, or based on pasture tick history. Livestock producers should work with their veterinarian to develop a tick control program. The American Veterinary Medical Association states no products in the United States are currently labeled for use against ALHT. However, several approved isoxazoline-class drugs for small animals and permethrin-class drugs for large animals have worked well against ALHT. Practitioners and producers are advised that use of these products for ALHT constitutes extra-label use and should be supervised by a veterinarian.
Pasture Management: ALHT thrive in mature or overgrown pasture grass. If ALHT are found, pastures can be mowed or harvested for hay, haylage, and baleage. Based on research, it is unlikely ALHT can survive at the moisture content of stored forages making this a potential option for producers, but this has not yet been studied. ALHT may survive at the edges of bales stored on the ground where moisture levels are high, potentially attaching to animals when they feed. Removing tall vegetation in a pasture will allow more sunlight penetration, resulting in a less optimal tick habitat. Rotational grazing strategies also reduce tick habitat.
Application of pesticides to pasture for tick control may be necessary. Several pesticides labelled for general tick control are available and can be applied to pastures. Because these products need to contact the tick to be effective, be sure that the product reaches the soil’s surface. Eggs are resistant to pesticide application and will hatch when conditions are optimal. If a pasture treatment is applied, scout for emergence of ALHT larvae or reintroduction of ticks in the following weeks. Most pesticides do not have a long residual effect so a second application—per the label instructions—can be applied to control emergence of larvae, minding any pollinator protections on the label. Currently there are no approved pesticides labelled to control ticks on annual cereal grains, cover crops, legumes, or corn used for grazing or making stored forage.
When using pesticides, remember that the label is the law. Please read, understand, and follow all label guidelines for use of pesticides to control ticks.
Centers for Disease Control and Prevention, “What You Need to Know About Asian Longhorned Ticks–A New Tick In the United States” at cdc.gov/ticks/longhorned-tick/index.html.
Ohio Department of Health, “Tickborne Diseases in Ohio” at odh.ohio.gov/wps/portal/gov/odh/know-our-programs/zoonotic-disease-program/resources/tickborne-diseases.
USDA Pest Alert, “Asian Longhorned Tick (Haemaphysalis longicornis)” at aphis.usda.gov/publications/animal_health/alert-asian-longhorned-tick.508.pdf.
Note: This fact sheet is supported by a grant from USDA NIFA 20217000635562