Question: I have recently discovered a small portion of my carpet has been chewed away.  it is located under a window and there is a hole that leads down to the cement.  The hole is maybe an inch wide.  There are no signs droppings.  There is a small garden outside of the window and there are often holes in the dirt.  What could have done this, would it be in the house?

ANSWER  Well, I suspect that this is damage caused by rats. A pest control professional could inspect and identify it more accurately. The local Orkin branch office can arrange an inspection.
 
If this is, indeed a rat problem, the most efficient solutions is to use snap traps.  Rats are shy around new things, so the traps must be very attractive. Bait the traps with small amount of food  and tie it on securely.

Put the traps in a rat runway, but make sure that children and pets cannot reach them. If there are more than one rat, the traps may need to be re-set and re-positioned several times until the rats have all been caught. Rat traps are VERY strong, so be careful when handling them.
 
Baits may be effective, but often the rat dies behind the wall and there is a lingering odor for several weeks. 
 
Rodent-proofing is the most effective prevention method. Inspect the home to find any opening that a rat could use to get inside. Rats can follow utility lines or tree branches to get onto the roof, and they can climb up downspouts.  Once on the roof they can enter the attic through un-screened vents.  They can move from room to room and apartment to apartment in the attic by following pipes.  All potential access points for rats should be inspected and sealed.