Can anyone help ID these?

​Mystery moth and even more mysterious dwelling

I'd like to be able to write about two creatures that fascinated me last week in La Serena.  The trouble is, I don't know what they are!

On the left is a caterpillar, one of thousands that were crossing the track between two fields of autumn-sown barley.  They were not processing nose-to-tail, but moving in loose herds, each group covering about ten to thirty metres of ground, separated from the next group by a hundred metres or so.

On the right is a hole about a centimetre in diameter.  In front of it the ground has been cleared, either deliberately, or by frequent passage of tiny feet.  You can just make out a horseshoe shaped collection of seeds around this bare area and behind the hole.  It is on the shaded side of a large stone, part of a line of rocks in an area of unploughed grassland.

Any help would be gratefully received and acknowledged!