Linda: I'm glad the Murphy's soap worked for you. I guess I (we) should always follow the caveat and test a substance on a small part of a plant before we use it. The Murphy's soap is a simple carbon chain with some oh group attached here and there. It works by dissolving the cuticle ( skin) of the beast and they desiccate and die. There are some potassium ions in the soap which may be responsible for the damage. I guess one of the chemist like Jim S. can comment more lucidly on the effect of a soap substance on living tissue. It also has a scent of citronella which may be a good way to chase mosquitos. Arnold