What kind of caterpillar is this?

Does anyone have any idea on what kind of caterpillars these are? They have been favoring our licorice plants in the garden. They have spun fibrous protective cocoons, so I thought maybe they are some sort of tent caterpillar, but I've never seen any with the spiky hairs.

Thanks!

http://imgur.com/5pO74.jpg

http://i.imgur.com/ecSkd.jpg

http://i.imgur.com/kdDHu.jpg