Are the lubbers in the New Orleans area Romalea guttata or micropteres?

I'd thought it was only the just-hatched lubbers that were red, but learned on April 12th that it's not so. Anybody know if it's limited to early molts, or does the black form come out of any molt brightly colored? Hardly a survival trait, one would think.

Is there a name for the whitish threads left in the outgrown armor?

A woman visiting the park where I volunteer ( http://www.nps.gov/jela/barataria-preserve.htm ) told me that when she was a girl, she would fill a matchbox with dirt and hitch it with thread to a lubber, which would pull the matchbox.