Scientific way to tell the difference between mail and female ants. Throw them in water.. Girl ants sink.. Boy ants float.
Here's a handy scientific tip. If you wake up in a strange hotel and want to know which hemisphere you're in just run the tap and see if the water drains clockwise/northern or anticlockwise/southern. N.B. If you're waking up without knowing which hemisphere you're in you should seriously think about your alcohol consumption.