Which life stage of a tick usually has six legs?

The life stage of a tick that usually has six legs is the larva.

Tick larvae hatch from eggs with three pairs of legs, for a total of six. After feeding, a larva molts into the nymphal stage and gains a fourth pair, bringing the usual total to eight legs. Adult ticks also have eight legs. This six-legged beginning is one of the clearest ways tick development differs from that of many familiar arachnids.

The larval stage is often called the “seed tick” stage because the animals are extremely small. Larvae seek a host, take a blood meal, and then drop off to molt. Nymphs are larger but can still be difficult to spot, and they are important disease vectors because people may overlook them. Adult females usually take a large blood meal before laying eggs.

Ticks are arachnids in the order Ixodida, related to mites. Their life cycle generally proceeds from egg to larva, nymph, and adult, although the number of nymphal molts varies among groups. Unlike insects, ticks do not have a pupal stage, so “pupa” is not a valid tick life stage.