How do ants build ant hills?

Brayden has been wondering about ants. Today, he wanted to know how they build their ant hills.

Here is what he learned:

• The ants that do the digging are all females. (Mom's question for tomorrow = what the heck to the boy ants do while the girl ants are so busy??)
• The way the hill is formed is the ants grab little bits of dirt and carry them outside the opening of their tunnel. They dig and dig and never give up, and slowly the dirt pile gets higher and higher!
• It takes 3 MONTHS to build one ant hill. That's a long time!

 Here is the picture he chose for this post:

 Sources:
http://wiki.answers.com/Q/How_long_does_it_take_for_an_ant_to_build_a_ant_hill#

http://www.ehow.com/how-does_4614712_ant-anthill.html

Image:  http://6legs2many.files.wordpress.com/2010/11/twig-ant-pseudomyrmex-group-workers-carry-food.jpg