Powerhouse

"Powerhouse" is arguably one of Raymond Scott's three best-known works, along with "The Toy Trumpet" and "Mountain High, Valley Low" (from the 1946 Broadway musical Lute Song).

First recorded by the Raymond Scott Quintette in 1937, "Powerhouse" was covered by dozens of orchestras and small jazz combos worldwide in the following decade. In 1943, Scott sold his publishing rights to Advanced Music, a division of Warner Brothers, and that year Carl Stalling began peppering his Bugs Bunny and Daffy Duck cartoon scores with Scott melodies — "Powerhouse" being the most oft-quoted.

We don't know why Scott sold his publishing, although money is a good place to begin any conjecture. He was probably advised to sell rather than initiating such a transaction on his own. Scott was obsessed with music and engineering (not necessarily in that order) and inclined to leave the paperwork to trusted associates. (Not that such associates deserved to be "trusted." Late in life, explaining his depleted finances, Scott remarked that someone "managed my money until I managed to not have any.")

Once the publishing belonged to WB, Scott had no further involvement with licensing, other than to collect writer's royalties. He surely had nothing to do with the use of his melodies in Looney Tunes. There is no indication that Scott and Stalling ever met, or that Scott was even aware of Stalling, though Stalling was certainly hyper-aware of Scott's music.

There's more info about "Powerhouse" at Wikipedia.