09/17/2026
You may have noticed a dramatic increase in the number of ticks you find on you or your pets in recent years. We have too, and while we work to keep everyone safe while recreating outside, we also want to figure out: why is this happening? š§
Ticks have found homes across the United States, and their ranges are still expanding. This can be attributed to climate change and disease vector control. When ticks feed on the blood of a vector of diseases, they are transmitted that disease. White-footed mice are hosts for larval ticks or nymphs, and they can spread Lyme Disease to those ticks, who spread it to their next reproductive host. There is a theory that when oak trees are in a mast year and produce an abundance of acorns, there is plenty of food for vectors like mice, squirrels, opossums, and skunks where they gather to eat and can spread diseases. The host species have more food, so they have more babies, and ticks have more hosts.
White-tailed deer populations in residential areas in Pennsylvania have also grown out of control due to a lack of major predators like wolves, bears, and coyotes, and decreased forest habitat. In terms of their impacts of tick populations, we know that deer are significant reproductive hosts for adult ticks, which helps support greater populations of ticks as there are more deer hosts available. Deer donāt necessarily spread diseases like Lymes to the ticks, but they do provide ample resources for adult ticks to make more and more nymphs. The deer travel with the adult ticks to human-populated areas, their nymphs find smaller hosts that do carry diseases, the infected nymph finds a human or pet as a host, and the disease spreads.
Climate change is also impacting tick populations and geographic ranges. As states like Pennsylvania see warmer and more humid summers that last longer into the year, we can expect to see ticks enjoying their ideal weather conditions and expanding their populations longer into the year. In the north where ticks previously couldnāt survive, as we see increasing average temperatures, we too see different tick species traveling farther north. While not new to Pennsylvania, lone star ticks have made a dramatic increase in recent years as our temperatures rise. One would think that the colder, snowier winters weāre seeing would work against the tick populations. Alas, ticks become dormant during winter months and survive by hiding under leaf litter under the snow. As we see heavier snow fall, the ticks get a āblanketā over them as they hide in the layer between the snow and the ground where itās a bit warmer. The snow also acts like a barrier between the ticks and any pesticide chemicals or their few remaining predators like overwintering birds or small mammals that arenāt hibernating.
We have at least 25 tick species in Pennsylvania, but not all of them are controlled well by predators. For instance, the Asian longhorned tick is a new invasive species to Pennsylvania, only found as recently as 2019. Because this species is from another continent, it has no natural predators to keep its population in check, and because itās new to Pennsylvania, weāre not sure what its preferred host species are or what diseases itās likely to spread. The Gulf Coast tick is beginning to expand into Pennsylvania and carries a spotted fever disease called Rickettsia parkeri rickettsiosis. Brown dog ticks are found throughout North America, but their typical habitat range is in the warmer southern and western areas of the country. These ticks are now being found more commonly in Pennsylvania and further north, where they can spread Rocky Mountain Fever to dogs, coyotes, and foxes.
For now, what we as individuals can do is take preventative measures and caution. Wear bug repellant, long pants, long socks, take showers after working or playing outdoors and do a thorough check for ticks, avoid walking or taking pets into tall grasses, and if you are bitten by any tick, remove it as soon as possible with fine-tipped tweezers. If you suspect the tick is a nymph, a blacklegged tick, or a lone-star tick (or any tick to be safe), keep the tick in a small plastic bag after removal and send it to a tick lab where professionals will test it for free in Pennsylvania. If you see any changes to the bite site, see a red ring around a spot on your body, or have any concerns at all, visit a medical professional immediately and seek treatment.
If you have any further questions or concerns about ticks, feel free to review the resources below, or attend the Health Department Tick Program being held at the Latodami Nature Center on September 22nd.
Resources:
https://stateline.org/2026/08/17/mice-may-drive-lyme-disease-more-than-deer/
https://doi.org/10.1111/1365-2656.70163
https://extension.psu.edu/know-your-vector-lonestar-ticks
https://redinational.com/how-effective-is-tick-control-in-snowy-conditions/
https://extension.psu.edu/common-ticks-and-tick-borne-diseases-in-pennsylvania
https://tickzone.app/ticks/gulf-coast-tick
https://extension.psu.edu/know-your-vector-brown-dog-ticks
http://ticklab.org/
