Tent caterpillars WILL destroy your trees. We have used the dish soap in a spray bottle technique and have gotten rid of them also.
However, this year I will take tent caterpillars instead deer ticks that cause Lyme disease. Because we had such a mild winter, the deer ticks have spread along the western Michigan coastline. Found one crawling on my family room floor....it had come off my DH jeans after he was in the woods. UGH! Scared to go outside now...