Europe's Most Dangerous Bug Hunts Mainly at Night, Study Finds

Scientists have discovered that the sheep tick, the most dangerous disease-carrying bug in Europe, does most of its hunting at night. This finding surprises researchers because most people believed ticks were mainly active during the day. The study was published in the journal Parasites & Vectors and is based on a year-long research project in England. The results could change the way people protect themselves from tick bites.

The sheep tick's scientific name is Ixodes ricinus. It is a tiny, spider-like creature called an arachnid, which means it is related to spiders rather than insects. This tick is well known for spreading Lyme disease, a serious illness that starts with a round red rash on the skin. After the rash appears, a person may get a fever, chills, headaches, tired muscles, and nerve problems. In some children, Lyme disease can even cause one side of the face to droop, a condition called facial palsy.

The tick itself does not make people sick on its own. The real culprit is a tiny bacterium called Borrelia burgdorferi that lives inside the tick. When the tick bites and feeds on blood, it can pass this bacterium along to the person or animal it bites. The tick can also spread other harmful organisms that cause brain swelling, known as encephalitis, and diseases in farm animals.

To learn more about when ticks are most active, researchers from the University of Liverpool and the University of Bristol ran a study throughout all of 2022. They chose Lyme Park in England as their study site. Every four hours, they dragged long fabric blankets across the ground to collect ticks. By the end of the year, they had gathered enough data to find clear patterns in tick behavior.

Ticks find hosts through a behavior called questing. During questing, a tick climbs up a blade of grass or a plant stem and holds on with its back legs. It stretches its front legs out wide, waiting to grab onto a person or animal that walks by. Once it latches on, it buries its mouthparts into the skin and begins to drink blood.

The researchers found that ticks did most of their questing during the dark hours of the night. They believe this happens because nighttime temperatures are cooler, and ticks do better in cooler conditions. Fewer ticks were active in the middle of the day, especially on warm days in May. The study concluded that during warm weather, the greatest risk of a tick bite comes at night and around dawn.

Moisture in the air also plays a big role in when ticks are active. During cool, wet months, ticks spread their activity more evenly across the whole day. But on dry nights, ticks buried themselves in soil or leaf litter to avoid drying out. This is because ticks do not have a good way to hold water inside their bodies, so they must find damp hiding spots to stay hydrated.

The night-time activity of ticks probably developed over thousands of years to match the habits of small mammals like mice and voles. These small animals are also most active at night in the UK, making nighttime a good hunting opportunity for ticks. This connection between tick behavior and animal behavior is an important clue about how ticks evolved.

These findings matter for anyone who spends time outdoors. People who hike, camp, or walk through grassy or wooded areas in the evening or at night face a higher risk than experts once thought. The researchers pointed out that summer evenings, when people are more likely to camp outside, are a time of especially high exposure. Wearing long sleeves, using insect repellent, and checking for ticks after being outside are all helpful ways to stay safe.

The research also has meaning for the future. As climate change shifts temperatures and humidity levels across Europe, the patterns of tick activity could change too. Scientists are calling for more studies at different locations to build a fuller picture of tick behavior. For now, the key message is clear: when it comes to tick bites, the night can be just as risky as the day.