TUCSON, Ariz. -- Border Patrol agents in southern Arizona found more than 2 tons of marijuana being transported on a semitruck with a livestock trailer.Agents at the state Route 90 checkpoint near Whetstone discovered the 4,450 pounds of marijuana Wednesday night. The marijuana is valued at $2.2. millionCheckpoint agents became suspicious when they noticed the ventilation holes in the upper compartments of the cattle hauler were plugged. Agents discovered 188 bundles of marijuana and a pistol. The driver was arrested.