I've mellowed when it comes to hornworms. My understanding is that they come in two waves, spring and late summer/fall. I did not have a problem with them this past spring, and I have yet to spot one but I have seen signs, namely frass on my zinnias and some minor defoliation of tomatoes. The hornworms seem to prefer zinnia foliage to tomato foliage.
Hormworms don't bother me as much during their late summer/fall wave because by then the established tomato plants have plenty of foliage and again they seem to target the zinnias more. As far as I know they are not disease carriers.
I do have some younger plants and I am vigilant with those plants to make sure that a hormworm does not get to them. Some other pests, cutworms and slugs I suspect, have been more destructive a bigger threat and they seem to go after peppers and eggplants more than tomatoes.
Starting last fall I relocated my hornworms and even took my pruned tomato leaves to the relocation area. I got the sads when I noticed that a parasitic wasp had gotten to one of the hornworms.
