I just came in from the garden, where I happily destoyed a few cabbage worms, & thought I'd post a "tip!"
I carry a small pair of needle-nosed pliers in my back pocket.
They are perfect for picking off cabbage worms, tomato hornworms, Japanese beetles-- any big slow critter I spy that shouldn't be where it is. I try to remember to take them with me every time I stroll through the garden so I can take immediate action. In the 3 minutes it would take me to go get them, if I forget, that tomato hornworm would destroy everything!
You can usually find this size in the "$2 and under bin" at the grocery, hardware, or big box store.