What attracts ticks to humans?

Ticks are attracted to humans by several cues that signal a host is nearby, using sensory organs to detect body heat, carbon dioxide, odors, vibrations, and movement. Primary attractants include carbon dioxide exhaled by humans and animals, which ticks can detect from distance, body heat and warmth from skin, and body odors including lactic acid, ammonia, and other chemicals in sweat that ticks sense with Haller's organ located on first pair of legs. Ticks are also attracted to movement and vibrations from walking through grass and leaf litter, and they wait on vegetation with front legs extended in behavior called questing, grabbing onto hosts that brush past. Dark clothing may make ticks harder to spot but does not strongly attract them, though light clothing helps detection. Humans who spend time in tick habitats like tall grass, wooded areas, leaf litter, and near deer trails are more likely to encounter ticks, especially during warm months from spring to fall when ticks are active, though some species active in winter. Pets can bring ticks to humans. To reduce attraction, use repellents containing DEET, picaridin, or oil of lemon eucalyptus on skin and permethrin treated clothing which kills ticks on contact, wear long sleeves and pants tucked into socks, stay on trails, avoid tall grass, and perform thorough tick checks after outdoor activities including scalp, armpits, and groin, and shower within two hours.