earworm

A tune that keeps replaying in one's head or that one keeps thinking about, especially if unwanted.

The chorus [of "Meeting in the Ladies Room" by Klymaxx] spawned an earworm so potent that women still mutter it as they exit for a bathroom break twenty years later.

"It's been haunting me," she said. / "Yeah, well," he said, weakly. "Sometimes tunes do that." [...] "I don't mean that I heard it once before and caught an earworm. [...]"

Ellipsis of corn earworm (“larva of the moths Helicoverpa zea (syn. Heliothis zea) and Helicoverpa armigera, which are agricultural pests”).

I had planned in mind to tell you [...] how I protected, that is, guaranteed, Evergreen sweet corn against the bud worm and the ear worm; [...]

The number of bollworms or ear worms increases greatly as the season advances. This indicates a need for hastening the maturity of all crops affected.

An earwig (“insect of the order Dermaptera”).

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; [...]

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.