The way Missourians interact with ticks is changing: Climate change is one of many factors
“It’s always a bad tick year.”
Deb Hudman with the Missouri Department of Conservation is standing in a large field behind the office where she works.
It’s about 8 a.m., but the sun is already beating down on her as she drags a tick flag — basically a large sheet of flannel — along the flat, grass-covered ground behind her.
“Ticks' number one enemy is desiccation,” Hudman said. “And so, if they're out in an area like this –“
She gestured to the ground around her.
“It provides a lot of cover, but it also gets a lot more heat. So, if in their shaded area they tend to do better.”
Desiccation is essentially when a living thing dehydrates to death, and because ticks have such tiny bodies, the heat presents more of a risk than cold temperatures. Hudman said the leaf cover on the ground during colder months provides enough warmth for the ticks to survive.
“They just hunker down for the winter," Hudman said. "They do quite well in the cold. They can even survive under water for some time.”
Hudman said Missouri is a utopia for ticks; it’s not too hot, it’s not too cold and the humidity is just right. And Hudman should know.
She recently conducted a two-year Missouri Ticks and Tick-borne Pathogen Surveillance Research study starting in 2021. People from across the state mailed her the ticks they found on themselves, their pets and in their homes.
Her project investigated what kinds of ticks were present in Missouri, where they were most prevalent and what diseases they carried. She was quickly dubbed “The Tick Lady,” and she received ticks from every county in the state.
Hudman said she’s heard a lot of people talking recently about an increase in ticks due to last year’s mild winter.
She said she used to think like this too, but, in reality, the impacts of mild winters and climate change on tick’s behaviors is a lot more complicated.
Molly Baker, the Vector-Borne Disease Surveillance Coordinator for Missouri, keeps track of all tick-borne diseases in the state. The most common are Ehrlichiosis, Rocky Mountain Spotted Fever and Tularemia.
She said the number of tick-borne illnesses in Missouri is on the rise – just like much of the country, but this could be due to things like doctors’ growing awareness of the tick-borne illnesses, the availability of testing and even changes in human behavior.
Baker said that it’s hard to give a direct answer to the question: Is climate change making ticks worse?
“It's really hard to predict, from year to year, what that might look like, and there are a lot of factors,” Baker said.
She explained that a very cold winter or a very mild winter three years ago may have more impact on today’s tick population than the season directly before.
That’s because ticks have a long lifespan of anywhere from one to three years. Basically, however long it takes them to have three blood meals, which are exactly what they sound like. They ingest the blood of a warm-blooded creature, usually a mammal, to move from larva to nymph to adult tick.
Baker says environmental things like temperature, humidity and weather do play a role in the number of ticks around, but so does the availability of food sources – like deer, and how those deer are moving through the state.
“And so climate change is just one of those factors that's going to influence it [ticks’ behavior],” William Nicholson said.
Nicholson is the team leader for Ecology and Entomology in the Rickettsial Zoonoses Branch at the Centers for Disease Control & Prevention. His team looks at Rickettsial diseases, which include Rocky Mountain Spotted Fever.
Missouri is in the top five states when it comes to cases of this disease.
Within the CDC, folks at the National Center for Emerging and Zoonotic Infectious Diseases are monitoring climate change’s impacts on the risk of infectious diseases .
“Mild winters, early springs, and warmer temperatures are giving mosquitoes and ticks more time to reproduce, spread diseases, and expand their habitats,” according to their website.
“If the average temperature increases by one degree, where will the suitable habitat be at that time?” Nicholson said.
“And so, we do think that ticks will probably move a little further north, but at the same time, we may have some reduction in areas that become too hot for ticks. So, you know, it's not necessarily only one direction.”
Meaning Missouri could theoretically end up with fewer ticks or simply different species of ticks – like the Asian Longhorned tick,which the Missouri Department of Agriculture confirmed has been throughout Missouri since 2021.
But again, Nicholson said it comes down to more than just changes in climate. Things like the fragmentation of forest land, human expansion, large wildlife populations and even just people wanting to spend more time outdoors is bringing humans into closer contact with tick populations.
Deb Human with the Missouri Department of Conservation agrees that climate change and ticks seems like a simple question, but it has a very convoluted answer.
Human behaviors are changing due to hotter, less hospitable summers and warmer, more temperate winters. People are staying inside more during the summer months and are more likely to be outside – and near prime tick habitats – during traditional winter months.
Which means hungry ticks looking for a blood meal will also adapt their schedule.
“They're just feeding and replicating, and they don't care if they're doing that in November or if they're doing it in March,” Hudman said.
And people are reporting finding ticks earlier in the spring months in Missouri.
Hudman also said that ticks are reported more when people are out and about – for whatever reason. In her recent research, there was an influx of ticks being sent in in the fall during hunting seasons, as hunters were closer to deer – and, therefore, closer to ticks.
She added deer populations and black bear populations are expanding in Missouri, “and deer are nothing but nurseries. There are 1000s of ticks on deer.”
In the end, climate change is probably impacting how we interact with ticks, but are there more of them? People still don’t know.
It’s likely, but it could also just be that Missourian’s awareness and preparedness continues to grow.
Overall? Ticks are survivors that “were feeding on dinosaurs,” William Nicholson said.
Missouri is still a great habitat for ticks, and Deb Hudman said that’s unlikely to change anytime soon.
“As weather warms, it's going to have to be a lot warmer before it causes a problem for the ticks.”
KBIA reporter Rebecca Smith and Missouri Botanical Gardens senior entomologist Tad Yankoski joined St. Louis on the Air to discuss what makes Missouri so hospitable to ticks and how we can protect ourselves from tick-borne maladies.
Tad also provided an update on the nearly 100 illegally transported Antilles pinktoe tarantulas that’ve been living at the Missouri Botanical Gardens Butterfly House since they were seized by federal agents in February.