Have you ever used yahooanswers.com its a great source for any question you might have...type in the search bar what question you want answered and it will give you a list of questions that were asked similar to yours...here is an example..
http://answers.yahoo.com/question/in...5153323AAp5CGs
Also read the last answer..not sure if he is right or not..but silkworms are native to Asia and wouldnt be what is killing your tree...
Dawn