Ticks are bloodsucking external parasites that feed on humans, wild and domestic mammals, birds, reptiles and other warm blooded mammals. They are totally dependent on the blood/tissue fluids of the host. The longer an infective tick feeds, the greater the chance of infection.
Ticks are not insects. Ticks have eight legs as an adult and two body segments, whereas insects have six legs as an adult and three body segments. Ticks are arachnids, as are chiggers, spiders and mites.
Ticks have four life stages: egg, larva, nymph, and adult. The egg hatches into a larva. A larva (“seed” tick) has six legs. It feeds and molts into a nymph. A nymph has eight legs and no sex differentiation. It then feeds and molts into an adult. The adult is differentiated into male or female. The female requires a blood meal in order to lay eggs.
A hard tick seeks a blood meal at, or slightly above, ground level by climbing onto vegetation and using its forelegs to feel/grab for a host. Ticks are usually found from ground level to three feet above the ground. A tick uses carbon dioxide, scent, body heat, and other stimuli to find a host.
To be infective (capable of acquiring and transmitting infection) the tick must be able to maintain the infection through a molt. Ticks vary in their ability to do this. For example, dog ticks can acquire the pathogen that causes Lyme disease – so they can be “infected”. But, they can not maintain the infection as they molt from one stage to another. Therefore, they are not “infective”.