Due to being adapted to live inside hair follicles, D. folliculorum is thin and worm-like, with short legs. As an adult, D.folliculorum measures 0.3 to 0.4 mm long. Adults have four pairs of legs; larvae and nymphs have only three pairs.

It was previously considered that D.folliculorum has a rudimentary gut but lacks an anus, so waste accumulates within the body until it dies. However, a 2022 study using electron microscopy and genetic analysis, confirmed that the mites do have an anus. This discovery means that Demodex mites can excrete