Hi Jane, I'm not a doctor, I don't even play one on television, but I get that from time to time, and it's not from bugs, it's from working with the plants. I can't tell you what plants in particular, more often than not, it will be from working around hedges/evergreens/small trees or perennial beds. It's another reason I think that I stick to containers for annuals, funny, I never thought of it that way before until your post. Usually, I shower, maybe I put something on it like witch hazel, and that's the end of it. I can understand your being very concerned, I've moved to an area with an increased tick population, and I'm very mindful of it, maybe even too mindful. But if you don't feel the bugs biting you or see them, it MAY be plant-based. How long does the irritation last? Again, I'm just throwing this out as a possibility that it could be something you really can't arm yourself against, or something that won't do you any real harm. That's supposed to be comforting -- I hope it is!