Songfacts®:

• This is the title track of the fifth studio album by The Shins. Vocalist James Mercer explained the song's meaning to the UK newspaper The Sun: "It's an attempt to express the feeling one might have when they're in love and don't want to be. The character in the song is losing his lover and can't figure out what to do about it."
• The Toronto Sun asked James Mercer why the record was named Heartworms. He replied: "In the song Heartworms there's this character who is in love with someone who is basically too good for them... And I remembered this band in the '90s I liked was called Heartworms. I liked it so much I named the album after them."
• The Heartworms title came to Mercer pretty late in the recording process. He explained to HMV.com: "I had a song that I'd decided to call 'Heartworms' and I really like the word. There was a band back in the 90's called Heartworms and I'd also really envied them for having that name, it's grotesque, but it sounds beautiful. So I contacted Archie Moore, who was the head guy for that band, he was in a few bands then, he was in Velocity Girl, and he let me use it. He gave me s--t at first about wanting to use it, but then he let me."
• The English post-punk musician Jojo Orme uses Heartworms as her performing name, taking it from the Shins album.