This is the favorite art project of many students. The videos and links are pretty self explanatory. It does help to add some soap and water to the ink. It also helps to get the straw more horizontal than vertical relative to the paper. The project forces people into creativity; into working with what they have. And its just a lot of fun too.
1. First: search google images for: Saturniidae moth caterpillar.
2. ink, and Other, Monsters