Controlling Caterpillars on Miniature Roses

Those "little green worms" are likely sawfly larvae or caterpillars. Two effective approaches:

Systemic Insecticide

Ortho Rose & Flower Insect Killer (or similar) moves into the sap. Any chewing pest ingests it and dies. Follow label rates.

Organic Suffocation Spray

1 tbsp cooking oil + 1 quart water. Spray thoroughly, especially leaf undersides and base of canes. Coats and smothers soft-bodied larvae. Repeat weekly until gone.

Both work. The oil spray is safer for beneficials if applied early morning or evening.