The pillbug moves like the queen bee - one space at a time - but it also has a special ability that it may use instead of moving. This ability allows the pillbug to move an adjacent unstacked piece (whether friendly or enemy) two spaces: up onto the pillbug itself, then down into an empty space adjacent to itself.  The mosquito can mimic either the movement or special ability of the pillbug, even when the pillbug it is touching has been rendered immobile by another pillbug.