I don't know that they have specific ways to navigate to the host plant but they definitely won't stop once they finish off a branch !! And they also don't just eat tomatoes! I hate touching them too but I make a bucket up of 1/4 cup Ivory dish soap per gallon of water - when I find a worm I pick it off and put it in the mixture - it kills them pretty immediately and then spray the rest of the plants with this mixture - It has worked pretty well for me this year ! But definitely don't keep them alive unless they have the white eggs all over their back because those eggs are the parasitic wasps that will kill the hornworms ! Hope this helps !!

I use my kitchen tongs. The ones with a triangle/loop at the end. Works great unless they hold on really hard and get torn in two.
Yeek.