Ticks eat blood, and nothing else. They are obligate blood-feeding parasites, meaning every nutrient they need to grow, develop, and reproduce comes from a single food source: the blood of a living host. Their hosts include mammals, birds, reptiles, and amphibians, making ticks remarkably versatile feeders across the animal kingdom.
Blood Is Their Only Food
Unlike mosquitoes, which supplement blood meals with plant nectar, ticks rely on blood as their sole source of nutrition throughout their entire lives. From the moment a tick hatches as a tiny larva to its final days as an adult, it feeds exclusively on blood. A 2020 study did discover that lone star ticks actively drink liquid water to stay hydrated between meals, which was previously unknown. Researchers confirmed the ticks were swallowing the water by mixing fluorescent dye into it and later finding the dye inside the ticks’ guts and salivary glands. But water aside, blood is the only thing on the menu.
How Ticks Find a Host
Ticks can’t fly or jump. Instead, they climb to the tips of grass blades or low vegetation and extend their front legs outward in a behavior called “questing,” waiting for a host to brush past. Carbon dioxide, the gas you exhale with every breath, is one of the most important signals ticks use to detect a nearby meal. Even at concentrations as low as 1%, CO2 triggers a strong response: ticks that are already walking speed up, while stationary ticks begin waving their front legs and start questing.
For years, scientists assumed ticks detected CO2 through a specialized sensory structure on their front legs called the Haller’s organ. But research published in 2024 found that blacklegged ticks responded just as strongly to CO2 even when that organ was disabled or the front legs were completely removed. This means ticks have CO2-sensing structures elsewhere on their bodies that haven’t been identified yet.
How They Feed
Once a tick lands on a host, it doesn’t simply bite and suck. The feeding process is a slow, carefully engineered operation. Ticks insert a barbed, straw-like mouthpart called a hypostome into the skin. Some species, like deer ticks, have longer barbed mouthparts that physically anchor them in place. Others, like dog ticks, have shorter mouthparts and instead secrete a cement-like glue that bonds them to the host’s skin.
The real sophistication is in their saliva. A tick’s body faces three immediate threats when it starts feeding: the host’s blood will try to clot, the wound will become inflamed, and the immune system will mount a defense. Tick saliva contains a cocktail of compounds that counteract all three. Some break down the chemicals that trigger blood clotting. Others block platelets from clumping together. Still others suppress inflammation, which is partly why tick bites are often painless and go unnoticed for days.
Feeding Duration and Volume
How long a tick feeds depends on what kind of tick it is. Hard ticks (the group that includes deer ticks, dog ticks, and lone star ticks) attach and feed for days at a time. Larvae, nymphs, and adult females all take prolonged blood meals, staying latched onto a host while slowly engorging. Soft ticks, by contrast, are built for speed. They typically feed for less than an hour before dropping off, and they don’t swell dramatically.
The volume of blood a hard tick consumes is staggering relative to its size. An engorged adult female can swell to 50 to 100 times her original body weight in a single feeding. Nymphs gain 9 to 80 times their weight, and larvae 7 to 20 times. This is possible because the tick’s outer covering has built-in folds and grooves that unfold and stretch as the body fills with blood, functioning like an expandable balloon.
Feeding Across the Life Cycle
Most hard ticks feed three times in their lives: once as a larva, once as a nymph, and once as an adult. Each blood meal fuels the transition to the next stage. A larva feeds, drops off its host, digests the blood, and molts into a nymph. The nymph repeats the process and molts into an adult. Adult females take one final, massive blood meal to produce eggs, then die. Males of many species feed minimally or not at all, focusing their energy on finding a mate.
Soft ticks follow a different pattern. They pass through multiple nymphal stages, and each stage requires its own blood meal. Adults may feed repeatedly throughout their lives, taking quick meals and detaching each time. This makes soft ticks more like repeat visitors than the long-term squatters that hard ticks are.
How Long Ticks Survive Without Eating
Ticks are extraordinarily patient. Between meals, they can survive for months or even years without feeding, depending on the species and environmental conditions. At room temperature, unfed adult blacklegged ticks survive up to 12 months. Lone star tick adults last about 8 months under the same conditions. When kept in cooler temperatures, survival extends dramatically: blacklegged ticks and western blacklegged ticks can live up to 24 months without a meal at refrigerator-range temperatures, and lone star ticks have been observed surviving over 2 years in cool storage.
The rabbit tick holds a notable record among the species studied in laboratory settings, with unfed adults surviving up to 18 months even at room temperature. This ability to wait is central to a tick’s survival strategy. Rather than actively hunting, they conserve energy, absorb moisture from the environment, and simply wait for the next host to pass within reach.