
Background
Three secret weapons make tick persistent survivor
It is time to be careful again: tick season has begun. The number of ticks (and the associated risk of Lyme disease) in the Netherlands is increasing slightly each year. In recent weeks, Dutch citizens have already started reporting tick bites. How can such small and slow creatures be so successful?
As the weather gradually improves, people flock to parks, forests and other natural areas. There, and in their own back gardens, Dutch residents get around 1.5 million tick bites each year. This is partly a matter of sheer numbers: a single tick can lay over a thousand eggs. But there is more to the story. Ticks have developed a few clever tricks that significantly boost their chances of survival.
Ticks have developed a few clever tricks that significantly boost their chances of survival
Front legs with a nose
First of all, ticks possess remarkable patience. Contrary to what many people believe, ticks do not drop from trees. Instead, they use a different strategy to locate a host. “They climb on blades of grass or twigs and raise themselves up, waving their front legs back and forth,” explains Sander Koenraadt, professor of One Health Entomology. This behaviour is known as questing. On their forelegs, ticks have a small depression containing tiny sensory hairs that detect odours. “As soon as they smell a potential host, they try to latch on as it passes by,” says Koenraadt. That host could be a mouse, bird, dog or human.
Biological glue
After such a long wait, a tick does not want to risk missing its opportunity. That is why it attaches itself firmly to its host, making it difficult to get dislodged when its host scratches or flicks its tail. Part of this involves choosing a spot the host cannot easily reach, like behind the ear or in a skin fold. On the other hand, the tick uses physical means so, once it has bitten, it does not just fall off its host. With its piercing proboscis, the hypostome, it bores into the skin, with sharp barbs ensuring that it stays in place.

“Ticks also produce a kind of glue in their saliva,” says Siddharth Deshpande, assistant professor Physical Chemistry and Soft Matter. A tick feeds continuously for between three and ten days, and the biological glue helps it stay attached throughout. You may have seen it yourself: when removing a tick, you sometimes also pull out a small brown cone with it, measuring about half a millimetre – this is the hardened glue. “While we already know that ticks produce such a glue, we are just beginning to understand how it works,” says Deshpande. “So there is still a lot we do not know.”
Ticks produce a kind of glue in their saliva
However, the researchers do know that tick glue starts as liquid saliva, which turns into a strong, anchoring substance within eighteen hours. This transformation is possibly driven by a specific family of proteins. Under certain conditions, these proteins could separate from other substances in the saliva and form protein-rich droplets. “You can crudely compare this process to oil in water,” Deshpande explains. “If you mix oil and water and then leave the solution to stand, they eventually separate into distinct layers.” In the case of tick glue, such separation results in an increasingly viscous material that eventually hardens into a resilient adhesive. How the tick detaches itself after feeding remains a mystery. “It might change the composition of its saliva to dissolve the glue,” Deshpande speculates. “But that is something we still need to investigate.”
Energy saving
Once detached, the tick can survive for months without food – unlike other parasites such as mosquitoes that need relatively constant access to a food source. “Ticks go through four life stages and feed only once per stage,” explains Koenraadt. “That comes down to just one meal per year.” Ticks manage this by dramatically slowing down their metabolism. Their bodies effectively enter a low-power mode, a handy feature when standing on a blade of grass for some time in search of a host. “It is also convenient for us in the lab,” Koenraadt jokes. “We can store ticks for extended periods without worrying about feeding them.”
So, the tick’s survival arsenal includes an internal energy saving mode to survive for months without blood, a sensitive ‘nose’ in its forelegs to detect potential hosts, and a barbed mouthpart with self-produced superglue to remain attached during feeding. Ticks may be small and slow, but their survival strategies are remarkably refined and effective. It makes them tenacious survivors, lurking in the shadows season after season.
The dangers of a tick bite
Ticks are carriers of a range of infectious diseases. About one in five ticks carries the Borrelia bacterium, the pathogen that causes Lyme disease. Each year, approximately 27,000 people in the Netherlands are diagnosed with this illness. Fortunately, a bite from an infected tick does not always lead to Lyme disease. The sooner a tick is removed, the lower the risk of infection.