In the life cycle of the chigger mite, which stage is parasitic and often affects humans?

The larval stage is the only stage in the life cycle of the chigger mite that is parasitic and significantly affects humans. During this stage, chigger larvae attach to their hosts, which can include various mammals, and feed on skin cells using stylostomes, which are tiny feeding tubes they create. This feeding process can lead to intense itching and irritation on the skin, often resulting in what is colloquially referred to as "chigger bites."

In contrast, other stages like the egg, nymph, and adult are either non-parasitic or do not interact with humans in a way that causes immediate health concerns. For example, the eggs hatch into larvae, which then become active parasites, while nymphs and adults are generally involved in the reproduction cycle and do not feed on host organisms. Thus, the emphasis on the larval stage highlights its unique role in the life cycle of chigger mites as the only stage that poses direct harm to humans through parasitism.