My garden is infested with tomato worms and they are gross. I found three today that were each FOUR inches long! Friday I was out inspecting the plants and saw no signs of the worms and then today I find 3 huge ones and 2 small ones devouring one plant! They grow fast and huge and what really sucks is that they are nibblers. They won't eat the seeds of the tomatoes so they will chew around the outside and then just leave the rest hanging on the stems...wasters.
How to get rid of the pests? Mostly I just put on my trusting gardening gloves and pull them off by hand dropping them into a bucket with a lid where they will die eventually. They are difficult to spot but the mangled branches, half eat tomatoes and little black turds everywhere are a good sign that one is nearby. But here is a little tip, if you see one that looks like the picture below, DON'T PULL IT OFF!
Those white things all over the back of the worm are the cocoon of the parasitic Braconid wasp and they are wonderful! The female wasp will lay her eggs into the tomato horn worm (it will also use flies, beetles, aphids and other wasps as hosts) and the larvae will eat the worms from the inside out and then spin their cocoon on the surface of the worm. The worm is alive during this whole process and will die soon after the adult wasps emerge leaving the worm dead, obviously, but most importantly unable to spin its own cocoon and then lay eggs as a moth.