Ear-worm

Earwig, [...] The ear-worm or grub, a well-known insect, with large transparent wings, which eats fruit and flower-leaves, and has been erroneously supposed to creep into the human brain through the ear; [...]

Source: wiktionary

Foreign Bodies in the Ear. [...] The ear-worm (forficula auricula), so much dreaded by people, occasions no special danger, but behaves in the ear in as harmless a manner as all other living animalcula of that calibre.

Source: wiktionary

She does not regard her ear-worms as anything other than an incidental irritant in her life. Unlike Jane, I have an ear-worm all the time – literally all the time – from the moment I wake up to the moment I zonk out; [...]

Source: wiktionary