Answer: You are describing a fruit worm, the larvae of a moth. Sevin is the chemical of choice but I say that with reservations because Sevin is lethal to bees and you need bees to pollinate your flowers. Bacillus thuringiensis (sold as Dipel) is a biocontrol that targets only caterpillars and doesn't harm other insects. It is a bacterium that acts as a stomach poison so the pests need to keep feeding in order for it to take effect. Either product will control the pests or you can simply scout your plants frequently and pick off any worms you see.
Best wishes with your garden!
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