The Pillbug may not move the piece most recently moved by the opponent. The Pillbug may not move any piece in a stack of pieces. The Pillbug may not move a piece if it splits the hive (violating the One Hive Rule). The Pillbug may not move a piece through a too-narrow gap of stacked pieces (violating the Freedom to Move Rule). Any piece moved by the Pillbug may not be moved at all (directly or via the Pillbug action) on the next player's turn.

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.