The Bug Jar is a Rochester club that some people call the Jug Bar but I don’t know why. Last week, as Xiu Xiu and the Dirty Projectors passed by their cancelled date in Buffalo in search of warmer bars, I made plans to make the trek northeast to see two of the most frighteningly insane musicians I know.

Xiu Xiu are not the band that you play when you wake up in the morning. They’re not the type of band you can sleep to or cook to or work out to. Their lyrics can be as cold as a wet blanket in January.

Or they can strike just the right notes and play to you, like acupuncture, and this can happen in the course of time it takes to get to the end of their newest CD, The Air Force.

In the case of the Dirty Projectors, I wouldn’t know which CD to listen to. Although I love all of the band’s work and have seen them a few times, I’ve never heard more than one of their album tracks played live.

I had a conversation in my head with the Projectors’ writer Dave Longstreth. I said, “How come you don’t play your old songs no more?” and he said “‘Cause I don’t feel that way no more.” When I really did ask him later, after a few drinks, he told me that a lot of people didn’t play their old songs. He had learned, or remembered, some new songs.

This was the coolest thing I heard all night. The Projectors played arrangements of some of their favorite Black Flag songs, “Rise Above” and “Damaged.” Longstreth said he couldn’t find the album itself inside the sleeve, so he played as much of the song as he could remember.

The result was exciting and electric. As the electric 12-string skitted away sporadic dancing notes, the two soprano singers sang interwoven melodies off one another. It was bizarre and the type of melody that is hard enough to mathematically decipher, let alone to sing from memory. These two women were beautiful and mysterious, and combined with Mr. Longstreth, created the delicate arrangements that the Projectors’ records have always resonated.

I had seen only one member of the band before.

After a performance by Cong for Brums (Xiu Xiu’s percussionist), Xiu Xiu took the stage, standing on a space all of three feet wide. While on stage, the band played what seemed like an endless list of instruments, from the electronic to the primitive, the novelty to the stringed. They played the piano part from The Air Force on the bells, an interesting segue into the rest of the set.

Just as on the band’s recordings, when you hear the music they create, you get scared. In between screeching some of his lyrics, Jamie Stewart played a stack of cymbals he kept at the edge of the stage with him. He hit them so hard that it was constantly startling, more so for those in front of the audience when the cymbal stand fell headfirst off the stage.

The show was intense, the lightest part of which came when Caralee McElroy hit herself in the eye with a drumstick. Finally the music was able to stop for a moment, and the audience, listening to every breath, could take one of their own.