The Chryssalid run distance in the ini file is 20. This translates into 13 squares of straight line travel for a half-move.
Dec 21, 2012 Initially, the Chryssalid's bite attack (deals 8hp) will only poison its target. IF the target, soldier or civilian, dies from either the initial damage or the resulting poison, his or her corpse.
See the detailed answer to the question.A basic soldier moves 15 squares in a straight line during a full move. Given a Chryssalid standing next to a soldier and a clear straight run in the opposite direction, the soldier should be able to full move out of range of the alien's half move, making the alien unable to melee this turn. The alien would have to full move and attack, which it can't do.Also note: Chryssalids ignore cover.
They do not seek it. They do not use it. Their attacks ignore it. Your soldiers can better support each other by also ignoring cover to get closer together.