Didn't know what kind of pest could eat up our guava tree almost the size of a foot thumb

I really didn't know what kind of pest could eat up our guava tree almost the size of a foot thumb? I was searching today in the internet hoping to find some answers or to the least clues to my question. Early on today, I found out new year 2012 January 1 that one of the foot thumb-sized branches of our guava tree has been cut by some pest.

It was really something odd as for the most years of my life living with plants and planting them, I have never encountered anything like it before. Guava trees are known to have stood up to the test of typhoons and even intentional breaking of its branches by anyone. It is known to widthstand any abuse I could think of for a tree so unbreakable but today, I found out that one of our guava trees branches was cut slice sharp by some caterpillar. Yes it was a caterpillar and I am still buffled by it like how Pacquiao could ever beat the big Margarito.