Final answer:
Eyelash mites living in human eyelids are closely related to spiders, belonging to the same group of arachnids as house mites and dust mites.
Step-by-step explanation:
Most healthy humans have several thousand eyelash mites living in their eyelids. These mites are closely related to spiders and are a type of arachnid. Specifically, these mites belong to a group commonly referred to as house mites, which also contain the common dust mite. Dust mites feed on organic debris including human skin and are known to be a common trigger for asthma due to the proteins found in their feces. While not all mites are parasitic, those associated with humans often exist in a delicate balance, and some species like the eyelash mites are considered largely harmless to their human hosts, living off dead skin cells and oils found near hair follicles.