Fans of Sheila and the Insects (SATI) may choke on their drinks and swallow their tongues upon hearing “Pretty Loser,” the newest single from the alternative pop group. At the very least, the song will not fail to snag one’s attention, while putting one’s back up. Leave it to SATI to break their lingering silence with an anti-love song. (Not counting solo efforts in between, their prior single came out in 2008, whereas their last album, Flowerfish, was released in 2005.) Twenty one years in the music circuit, off and on, has not mellowed the band. They still sound as belligerent as punks, with a light coating of jaded sophistication.